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What to do with a student coming to class in revealing clothing, to the degree that it disrupts the teaching environment?
Since semester started, a female student has been attending classes scantily clad or wearing clothes that are too revealing, like a sport bra without shirt on top, booty shorts, semitransparent silk blouses without a bra, or even a bikini (this situation happened only once.) She does this once or twice every month and, apart from wearing revealing clothes, she behaves as any other student. My university is located in a fairly liberal country and I'm not a prude. There is no written dress code. During summer, crop tops and shorts are the norm.
In a previous question, someone brought about an issue regarding a student wearing an offensive shirt, but the answers to that question doesn't apply here. First, what the student is doing isn’t illegal like wearing a racist slogan and she isn’t underage; second, in the linked question, the TA was a female who feared becoming a victim of aggression. In my case, I am the male and I fear the if I tell the student I am not comfortable with her clothing, she might consider it harassment; third, she does this in plain view, not only in my class, and not during office hours (like here) so I don't have reason to believe I've been somehow targeted be her.
This situation is disrupting the teaching environment - students start talking and leering instead of following the class. I have noticed that my students' level of attention and the class speed is significantly lowered when she comes wearing revealing clothes. It may cause issues outside the classroom, too. Recently, during my office hours, one student asked me my opinion on her, to which I replied that, as a TA, I had to remain non-judmental (and that he didn’t have authority to ask such questions.) Then the student told me rumor has it I haven’t intervened because I enjoy watching the student expose herself. You get here the subtlety of my situation: If I intervene, the student may consider I'm harassing her; if I don’t, I could become that perv who likes peering at his student.
The department’s head says that I can let the bikini pass once, but that he will intervene if it happens again. He cannot do anything regarding silk blouses or sport bras, though. He will intervene only if the situation escalates, but I have authorization to intervene by myself to guarantee the class objectives are achieved.
Am I overreacting? If I let things go on as normal, will my students eventually assume I don’t care? If I'd have to talk to the student, how is the best way to address the situation considering gender issues?
EDIT: It's true what StrongBad says, that the other students have their part in disrupting, but I'm certain that the student wearing revealing clothes also wants to elicit a reaction (whether it is disrupting the class, I don't know.) We are in winter now, so she comes fully clothed, changes her clothes once in the building and always sits where everybody sees her. Outside classes, she is fully clothed. Her behavior is 100% intentional and she knows that when wearing that kind of clothes the environment of the class will accordingly change.
UPDATE: I’m a bit surprised that none of the upvoted answers address any of my questions. Most of them are on the line of “do not be judgmental and tell the other students to behave”, which is what I have done: My approach has been not to brought additional attention on her. If someone is giggling, I would call his attention in general terms, but I would never expose the student in front of her peers with a sentence like “Stop looking at her clothing and pay attention to me”. That would be harassment. It’s also true that the student has the right to wear whatever she wants, and that other students should behave, but human concentration has its limits and I cannot blame anybody for that. If a disruption is too constant and obvious, students will eventually fall. Stephan Kolassa made an analogy that I'll borrow here: “Everybody is within their rights not to shower. But if someone stinks so badly that other students cannot concentrate, I would say the instructor should attempt to change that one person's behavior - not expect that the entire rest of the class adapts their utterly normal reaction.” Pete L. Clark has also a good point when saying “the instructor can actually talk with the student and get her to understand why what she's doing is almost certainly not in her own best interest”. That would save the student some headaches in the future and allow me to appropriately teach my class. Furthermore, my department's head is well informed about the issue and has given me authorization to talk with the student. So now the onus is on me. To avoid starting a bureaucratic storm, most classroom problems (I think almost every problem in an academic or business settings) are solved in a bottom-up fashion. First TA intervenes and if it doesn't work, you escalate to the next level.
RESOLUTION: After many months, I'm writing again to tell what happened, but I can't give many details. After finals the student offered sex to another male TA. We had all made complains by then and got writing answers; we had our *ss covered. The student has been suspended. Moral of the story: get instructions in writing.

I'm sure this is fun to talk about and all, but please remember what comments are for on Stack Exchange and what belongs in chat instead. Conversation has been moved to chat, further conversation in comments (except comments asking for clarification) will be deleted, as we can't move comments to chat more than once.

Sigh, we are at 19 answers already. Folks, could you please check that your proposed course of action hasn't already been suggested before posting a new one?

(Meta post discussing this question: http://meta.academia.stackexchange.com/questions/3627/)

"During summer, crop tops and shorts are the norm. I myself come to university wearing sandals and shorts.", liberal as your country may be, teaching classes in sandals won't give you any respect as a teacher. Maybe she's even doing this "inappropriate clothes" thing as a confrontation to your lack of professionalism on the job: a university teacher.

First thought this is a fake post. Then considered that practically every woman's clothing reveals having breasts, which can be exciting to men if you are susceptible for that. Then found similar reports, e.g.: http://www.vox.com/the-big-idea/2017/3/31/15132730/pence-women-alone-rule-graham-discrimination

I hope others will not think this is an abuse of the comments section but I want to thank you for updating this question as the situation evolved. Reading the real-world outcome of the situation based on your course of action is just as valuable as seeing the result of an experiment that others have only theorized about.

I'm not at all sure the moral of the story is what OP says it was. First, it's not clear in what context that student "offered sex"; maybe she just hit on a male TA, and was suspended for doing that? But even if she tried to offer an exchange of sex for some kind of academic benefit - she did not complain about anyone leering at her; and it's unlikely she would complain if her offer is refused (blackmail is much more dangerous than currying favor through sex). So I'd say the moral of the story is "Communicate with your peers and perhaps your superiors about the situation to avoid risk."

@TheBerga: Disagree. Some of the most respected Professors I've known wear sandals and shorts in the summer.

@einpoklum The OP said that "we had all made complaints by then".  Instead of quid pro quo sexual harassment as you've suggested, I don't think that it seems too much of a stretch to think there could have existed some form of hostile environment sexual harassment on her part, according to the university.  Her offering sex may have just confirmed that as a reasonable interpretation.  But, of course, I don't know.

What country is this? What type of college? Is this person from a minority, or rich spoiled kid?

Ignore everyone here and ask your higher-ups what to do. Then do it.
And get at least some of the responses in writing so that you can point back to them.
I believe this is the only correct and safe way to proceed. End of story.

I'd add that you might even ask them to intervene directly.

@Mayou36: I agree except in the question the OP states he's already done that. I'm just baffled why he doesn't seem to have asked what he should do.

In addition to higher-ups, also ask a relevant university counsellor, as outlined in xmp125as answer.

Many existing answers recommend to refer up the chain of command. That big statement at the top of your post seem unwarranted.

This is a correct answer to many questions on academia.se. :-)

@CapeCode well, technically his advice to "ignore everyone here" will also apply to his own answer, so it is not logically consistent when interpreted literally. But if you turn off your math/exact sciences brain and stop interpreting things completely literally (it's hard, I know...), that big statement at the top does make some sense IMO.

@CapeCode: The existing answers also insert their on $0.02 on the issue, they don't merely say go talk to your superiors. I'm trying to make a point that their opinion is irrelevant and there's only one way to proceed here, so I do think that warrants what I wrote.

If you're going to do whatever your superiors suggest, rather than use your own judgment, then the part about getting it in writing is important. I once had some classroom issues, asked my principal, vice principal, and teaching coach what to do, did what they said, and then got in trouble for it. They denied ever having given me the advice.

@DCShannon: I agree, that's why I bolded it.

OP has stated that they have already taken these steps and the details have been added to the question.

This answer is a cop-out. Higher ups are not infallible gods, and they don't always have the right answer. They are plenty likely to give you the wrong advice/order, and you have a moral obligation to weigh their orders against your own conscience. The question has two aspects: what is the right course of action, and what is the safest course of action for my career. To ignore the second aspect is naive, to ignore the first is spineless.

@Peter: This is Academia.SE, not Morals.SE or Ethics.SE. I was trying to offer a solution to the problem, not to provide an ethical assessment of the situation. And In My Humble Opinion this problem's solution is what I posted. I don't think that's a cop-out, but if you do then post your own better answer.

@Peter (our matching names might confuse some people...) The situation of the OP doesn't require a right/wrong answer, so it doesn't matter if what the higher ups say is right or wrong. The OP is in a minefield, with no way of knowing where the next mine is, and asking a higher up to provide guidance in writing means letting them defuse (or step on) the mine instead of the OP.

@Peter He is in a both a moral and a and career minefield. If the higher-up suggests that the girl in question should get a failing grade (extreme example), that doesn't mean he should follow the advice blindly. Even if it's in writing. What if the higher-up doesn't know what to do and posts a question here? Do we tell them to ask their manager, all the way up to the president?

@Peter To be clear, I agree that the OP should definitely ask the advice of his supervisor, but that's not really an answer to the broader question. And "then do it" suggest that he should blindly follow orders, when he should ask for advice rather than instructions.

@Peter: "What if the higher-up doesn't know what to do and posts a question here? Do we tell them to ask their manager, all the way up to the president?" ...we can worry about that situation when it arises. "If the higher-up suggests that the girl in question should get a failing grade (extreme example), that doesn't mean he should follow the advice blindly" ...I have a sneaky, sneaky assumption I pulled on you here. I'm assuming the OP is not a robot who would, based on this answer, also jump off a bridge if a higher-up gave that advice. My apologies for not stating that. You caught me!

@Mehrdad: I quote: "Ask them what to do, then do it." I'm not objecting to telling a higher-up about the situation, but someone with an academic eduction, and the responsibility for a class of students, cannot simply ask a grownup what to do. Your answer explicitly states to ignore any answers here that actually pertain to the situation, and to simply do what the higher-up says. You may not have assumed that the OP is a robot, but you are telling him to behave like one.

@Peter: I have nothing to say beyond my last comment. Use your common sense as to what I meant.

Unlike my answer here, your problem does not seem to be about the clothing, but rather the disruption. Assuming the student is not breaking the university dress code, then it is not her who is disrupting the teaching environment, but other students.
You have not provided examples of how the response of the other students is disrupting the teaching environment, but the solution really doesn't matter that the cause of the disruptive behavior is the appearance of another individual. Simply remind students that the disruptive behavior (talking, hooting, leering, taking photos) is disruptive and will not be tolerate. If the students continue to be disruptive, throw them out of class.

Comments are not for extended discussion; this conversation has been moved to chat.

"Assuming the student is not breaking the university dress code, then it is not her who is disrupting the teaching environment, but other students." How does this logic work? When you're in a class your brain gets disrupted conditionally based on school policy, and you think "oh just kidding, false alarm, this isn't disrupting me because the school policy allows it"? Does it go on a meta-tangent and start wondering "should I be disrupted right now"  when it doesn't know the exact policy?

The best thing you can do is the escalate the problem to your superiors, which you already  did. Note that in disputes like this (when there is a bad and a worse choice, like you being accused of being either a harasser or a perv) the important thing is to let know your employer that there is a problem. That may be very important for your defense if you are forced to intervene if she starts to behave even more provocatively. So make sure that you have indisputable proof that you notified your superiors of a problem early.
Perhaps I would go even further. If you live in a liberal EU country, you may have dedicated university services taking care of sexual harassment, gender equality and similar. If you feel uncomfortable with her behavior, turn the tables on her, and go to the sexual harassment counselor and notify them. Gender equality goes both ways! If you (or your male students) would come into class in spandex swimming trunks, exposing the outline of your genitals, I believe the women in the audience would rightly feel this is inappropriate and constitutes harassment. So go to the counselor and report the situation. The counselor will have perhaps more knowledge how to tackle this or even she (it is probably a woman) will take the matter into her own hands.
As with your superiors, this may protect you if the girl starts acting even more unreasonably and you will have to intervene on short notice.

I think the second paragraph outlines the optimal option.  Not only notify the counsellor, but also ask them for a recommendation and follow that.  Or even ask them to talk to her directly if they do recommend to take action (which I would not expect).  Keep evidence of this communication.  That way, if you are accused of inaction for being a “perv”¹, you can hide behind the back of the counsellor and show you followed their advice. (¹I see no perversion in an adult heterosexual male being distracted by a adult female wearing revealing clothing)

The OP already went to the head of department who outlined conditions on which they would intervene. My read was that the OP was not feeling harassed (otherwise it is a duplicate to the linked question), but worried about the mm disruption.

@StrongBad Well, intervention by head is something, but the OP is in real difficulty if he has to intervene if the girl shows up again in the bikini and the situation escalates (teasing, harassment towards the girl). And merely defusing the situation in real time may put him in a very difficult position. Therefore, it should be clearly documented that he notified the appropriate authorities (person tasked with prevention of sexual harassment, if there is one) in time. Maybe they (the authority) will even invite a girl to a chat, for her own benefit.

There is no issue with telling students to stop harassing another student. As long as the students appearance is not harassing the other students (and a bikini falls into this category), you can always deal with it after the fact. While the authority might invite the student for a chat, in an ideal world they would invite the students who are being disruptive for the chat.

@StrongBad If a student wears a swimsuit to a classroom based lecture the instructor is well within their rights to question why they are doing it since it would cause a disruption to other students.

This is a cop out. The superior will face exactly the same question. It's the teacher's responsibility and authority to bring the student in line. Tell her to dress respectfully. That's the end of it. And as a side note, when the superior visits this site looking for advice, and (s)he follows it, you'll get a recursive loop all the way to the chairman, whose role is way above dealing with this issue.

this answer is laughably ridiculous. if the student is dressing within the dress code (it sounds like she is), there is simply no possible way she could be harrassing you. what misguided logic. the best course of action is, of course, to GET OVER YOURSELF (and possibly your childhood) and do nothing. (waiting for this comment to be deleted in 3.. 2..)

@sgroves you are sadly mistaken about the standards for harassment. At least for men, it is quite obvious, rightly or not, that the standard of what constitutes the harassment is decided by the the potential harassee population (women), not the harasser. Asking your female colleague out is not harassment per se, but do it repeatedly 10 times after she refuses each time, and you will be referred to counseling or worse. Yes, revealing clothing or even bikini on a hot summer day is one thing, doing it systematically, is quite another.

@xmp125a that's certainly one opinion. i disagree. there's a dress code. the student is following it and not otherwise doing anything wrong.

I'm somewhat surprised this hasn't been stated yet.
Wearing a bikini to class is inappropriate.
Period.
Just as wearing shorts, sandals and nothing else would be inappropriate. The classroom is not the place for swimwear.
This should have nothing to do with sexism, or with harassment (though I certainly understand why you're worried about that). It has nothing to do with "the students are at fault for noticing". It has nothing to do with "but men could do it" (no, they couldn't). It is not a case of "it's the mens' fault for suggesting that she was asking for it" (ridiculous).
Wearing bikinis, or transparent tops, or just bras is so obviously not okay. If I were in that position, I would feel quite within my rights to invite the student to my office and explain that she is in a semi-professional environment and is expected to dress accordingly. Besides everything else, she should be showing a little decorum and a little respect for you, the teacher. If she feels that's "harassment" then, frankly, bring it on. I can't imagine you'd lose that fight.
Whether that's something that works for you, in your culture, at your institution, in terms of the risk of fallout, I cannot possibly say.
But think of it this way: what would happen to her if she wore that to work?
Go from there.

Comments are not for extended discussion; this conversation has been moved to chat.

It seems like a terrible idea to invite her to your office to discuss in this situation...

I concede that statements such as "If she feels that's 'harassment' then, frankly, bring it on. I can't imagine you'd lose that fight" have, unfortunately, been proven laughably incorrect in the twelve months since this answer was posted.

I think that it is useful to view your dilemma from a worst-case scenario perspective.
Trying to intervene and the student then complaining about harassment/freedom of expression/etc., may (conceivably) lead to adverse professional consequences for you. For example, she might make a formal complaint with the risk that you are not employed again as a TA.
On the other hand, not intervening leaves you open to the somewhat indirect accusation that you didn't do something because you enjoyed her dressing as she does. I too would hate to think such a view was incorrectly held about me, but it is hard to see how much can come of it. Particularly, because one can easily imagine that your head of department, etc., will have no difficulty in understanding why you didn't intervene.
There are, of course, consequences for your students too, but as @StrongBad suggests they are responsible for their leering, not you. If they genuinely feel strongly about her dress, as opposed to it being a source of entertainment, and they can articulate a good reason why they do, then they can complain to someone up the hierarchy who may be in a more secure position from which to intervene. You might even consider subtly encouraging them in this direction.

There is a worse possible scenario if the OP doesn't intervene: the student could file a formal complaint stating that she feels harassed (for example) because he (allegedly) stares at her breasts during class. Probably still not worse than scenario 1, of course.

Allegedly stares at her breasts, which she exposes nonchalantly.  One should not judge someone by what they wear, but at the same time one should be aware of how others will react to what you are wearing.  Hate to break it to people but exposed(via transparent clothing) breasts tend to draw both male and female attention, especially in a college environment, as it is not something that would be expected in that situation.

Technically, according to the OP, one student already kinda complained about the whole situation.

You say that you've talked to your department head about this; make sure you get the answers in writing to protect yourself.  A student who changes into a bikini once she enters the building is a very different situation than a student who wears normal but revealing street clothes to class - make sure this information is included in your letter to your department head.
As you are aware, there is a fine line in enforcing dress codes -- nearly all school dress codes focus on limiting the freedom of female students to protect male students from distraction.  Your bikini-wearer is deliberately pushing the boundaries.  (I can't imagine that swimwear is allowed in class -- perhaps the situation has never come up before?)
If your male students ask privately, simply say that you're unfortunately not legally allowed to intervene. You may want to suggest to the most distractible students that they sit in the front rows to avoid having the bikini in their line of sight.
Does this student wear revealing clothes to other classes, or just yours?

She has worn revealing clothes to other classes, but the bikini incident only happened to me and so far I am the only TA who has complained to the deparment's head. She sits in the front row.

Do cover yourself by going to HR and asking for advice in writing. She may be planning to try and get better grades by blackmailing you, or something equally nefarious. And whatever you do, never be alone with her. If she insists on visiting you in your office, leave the door wide open. Try and have a colleague with you.

@je_b I might recommend telling the students that you are professionally not allowed to intervene and that if the students are seeing a problem to try going to the head of the department in general. Not that they should report you but that you are not the authority on this issue. I'm sure a dean of students or something can at the very least call the student in if enough people complain. After all, if the male students are uncomfortable and it is done on purpose it could be taken as harassment on her part towards the rest of the class.

You really need to get other members of staff, HR, your boss, to sit in on your lectures and see this first-hand. This problem is way over your pay-scale - you could easily lose your job if you mess it up - get the professionals in. Let them earn their wages for once.

Generally in professional environments, there is either an implicit or explicit prohibition on men commenting on how women are dressed. You are encountering that in the answers you are getting. That being said, this update to the question caught my eye:

We are in winter now, so she comes fully clothed, changes her clothes
  once in the building and always (clothed or not) sits on the first row
  so everybody sees her. Outside classes, she is fully clothed. Her
  behavior is 100% intentional and she knows that when wearing that kind
  of clothes the environment of the class will accordingly change.

To me this implies that the student is explicitly behaving the way she is in order to elicit response, either from you or the other students in the class. The fact that you mention a student asking about the situation implies that other students are noticing the disruption from the classroom norms.
Unfortunately as Pete L. Clark mentions, directly counseling the student on the fact that their behavior is against their own best interests even if it is explicitly permissible is very difficult to do without a lot of practice. I would advise you bring the situation up with the department chair and relevant university authorities to guard against an potential complaints against you. Additionally, you may want to reach out to your colleagues to see if one of them can approach the student to see if they can find some insight into why the student is choosing to dress in such a matter.

Lots of people wear one thing on their way to work and change when they get there. Further, there are lots of reasons to sit in the front row. Seems a bit extreme to conclude the student is attempting to elicit a response.

@StrongBad: "illicit a response" is an amusing typo that both you and anonymous have now made.

@PeteL.Clark in my defense, I copy and pasted the original sentence into my comment and then edited. When I saw your edit, I decided I better fix it in my comment too.

"Additionally, you may want to reach out to your colleagues to see if one of them can approach the student to see if they can find some insight into why the student is choosing to dress in such a matter." +1.  Maybe the best single suggestion I've seen across many answers.

@StrongBad Based upon what the OP wrote and I quoted I'm assuming that the student is dressing in an atypical matter when attending class. If the student is only wearing reveling clothing in the classroom and not, say, when at lunch on campus between classes, it would imply that they are doing things on purpose. Note that I didn't say anything where the student was sitting, it's just a block quote.

@StrongBad that may be true, but changing into swimwear and not wearing a shirt to class are two things that are incredibly distasteful. It's definitely strange behavior and it sounds like it is intentional. Bad taste is one thing but the OP is saying the clothing is revealing to the point of being half-naked at times. That's pretty intentional.

Meet the problem head on.  Take a couple of minutes to talk about it.  Remind your students that in this country (whatever country that is), students have the right to dress as they please, and if anyone has a problem with that, it's their problem, not the person with an unusual outfit's problem.
The most important thing is to convey a firm commitment to individual liberties and gender equality, and your expectation that everyone in the class behave in a supportive way to all their fellow students.
If you want to include some gentle humor to break the tension, that would be okay.  For example, in my case, I might share a memory of Professor R. who expressed his individuality by wearing a suit and tie, on teaching days and office days, alike: three-piece, dark wool generally, but with a switch to light blue seersucker on Memorial Day.  That was just his style.  To each his own, and who am I to tell anyone else how to dress?
Or you could mention that if Imelda Marcos paid her tuition and met the prerequisites, she would be welcome in your class, along with her entire collection of shoes.  (1220 pairs!)
(Ignore the rumors.  There will always be silly rumors about instructors.)
Edit, having read the edit to the question:
You are apparently considering speaking to the student one on one, to attempt to guide her towards a more conservative outfit in your class.  But you commented:

I would never expose the student in front of her peers with a sentence like “Stop looking at her clothing and pay attention to me”.

Correct.  That wouldn't be constructive!  When speaking to the whole class, it would be better to first convey your personal commitment to diversity in education, with an I-message, and then, if you're comfortable, allow some natural humor about the situation to surface.
I've read quite a bit about Tourette Syndrome, a neurological disorder that manifests as bizarre behavior.  One of my favorite fact sheets about Tourette, published by www.tourettes-action.org.uk, says:

Try not to respond too much to tics as this can normalise them.
However, often tics are humorous and it would be unnatural not to recognise this.

My son has Tourette's, and we've learned that the best way to help other people deal with his unusual behaviors is to explain to them what's going on, in a matter of fact way.  But, as the fact sheet says, some of his tics are funny, and I have found it helpful to allow myself to acknowledge this -- without giving the child too much positive feedback (which would encourage even more expression of the tics).
Humor is a great way of defusing tension.
You asked:

If I were to talk to the student, what would be the best way to address the situation, considering gender issues?

I would not advise doing this.
I just got a brainwave, and realized that perhaps you are not from the US, but are attending a university in the US, where you are a TA.
Perhaps there are some cultural differences at play here.  If so, please pass the problem unequivocably to your department administration.
(When I wrote my original answer, I don't think I had understood that you are a TA.  TA's are apprentice instructors, and should not be left to their own devices to meet such major challenges on their own.)

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The majority of this answer is not related to the issue described in the question.

@CapeCode - I would ask you which parts seemed irrelevant or unhelpful, but since you apparently think those parts make up more than half of the material, I will instead ask which parts seemed relevant or helpful.  Without that, your comment gives me the heavy hammer of judgment but doesn't help me figure out how to communicate my ideas about this question more clearly.

To prepare for the humor part, watch any google results for "the problem with jeggings" ... and the significantly step back from that

"The school doesn't have a dress code, we simply expect students to conduct themselves professionally. Unfortunately it appears that you come to class occasionally dressed in a manner which distracts attention from the lesson to you. I've discussed this disruption with my superiors at length.  We don't want to infringe on your personal expression.  We also don't want the other students to be distracted. We don't believe the distraction is intentional, and perhaps you're surprised to learn of it now. Regardless, we have to come up with a solution that is reasonable and fair for everyone."
From there the discussion will depend on what she says.  I doubt you'll need to prompt her to contribute her perspective, but if you do you might ask whether she needs help understanding the cultural norms of those attending the class, or simply ask her what her thoughts are.
If she becomes defensive, it sounds like the university doesn't provide you with much support in this case.  It might be best to simply say, "I understand you aren't breaking any rules, and I cannot ask you to change your behavior.  I"m hoping you understand the issue, and I will continue discussions with school officials to find a solution."
If she is amenable to change you might consider solutions such as sitting in the back of the class. If she wants to help but simply doesn't understand what outfits are distracting you might be able to come up with a word or action (putting a pencil on a specific spot on the table or lectern in front of you, for instance) that would encourage her to move seats if she actually is causing a disturbance.
Without specific knowledge of the university's policies, though, there's little else that can be recommended.
Having the discussion and understanding whether she understands the situation and is interested in changing is probably the key to the type of discussion you're hoping to have.
I'd strongly avoid mentioning specific outfits, or trying to draw lines between appropriate and inappropriate.  Always keep the discussion away from boundaries and focus on the fact that it's disruptive to the class. You should be prepared to explain what the class does in response to her outfits that demonstrates the disruption.
If the situation doesn't improve, and you can't simply wait out the semester, discuss further options with your superiors. You should be able to take some actions for the benefit of your class at your discretion, for instance having assigned seating throughout the class.

Arrange with a female TA to be present at the time you ask her to meet you in your office or some other appropriate space "for a couple of minutes."
When she arrives, simply tell her that you are in a difficult position, because the way the other students react to the way she dresses in your class makes it hard for you to teach effectively.  Tell her the objective measures to support this: the class pace, etc.  Acknowledge that she has the right to dress the way she wants.  Ask if she could help you.  Understatement is your friend here.
In the U.S., I would probably say "I'm guessing you're not surprised that, sometimes, other students are very interested in looking at you, because of the way you sometimes dress.   But you might be surprised to know that when that happens, the class goes more slowly, and the other students don't pay as much attention to the lesson they're supposed to learn.  My job here is to give them the best chance to learn what I'm teaching.  I"m not trying to tell you what to do.  I am just asking you to please help me out.  I would really appreciate it.  That's all."  Then I would indicate non-verbally that I had nothing else to say, and she could reply or not.  Adjust for whatever is culturally appropriate where you are.
You are a person with a problem, and you're asking her for help that she can easily give.  There's no guarantee she will, but it's a respectful place to start.  You might be surprised by the huge percentage of people who will do what you ask, if you simply ask them for help.
The female TA should preferably be sitting somewhere at a slight distance where she's not obviously participating, but can obviously hear, reading.

but it's not that she needs to help. She is the source of the problem. If she refuses to stop and continues to do it repeatedly, I would remove her from the class. It's not discriminatory. Her decision disrupts the class. The head of the department said the TA could do whatever was necessary to protecr the class from disruption from her.

@TheGreatDuck, you are simply wrong that she is the source of the problem. Other students, and even the instructor, are in control of their attention; if not, then that is a source of the problem. And society trains men to believe that any female flesh in their perception is relevant to their own sexual desires; that is a source of the problem.

@GregMartin She's the source of the problem when she intentionally: changes into the revealing clothes -> comes to class -> changes out of the revealing clothes. Regardless of sexual issues she is still intentionally wearing unusual clothing intended to catch the eyes of the class and make a scene. If she merely wore it at school until she went home or to work one might argue they are work out clothes or that she has no time afterwards to change. However, she only wears them in class which definitely makes it look intentional which means she is causing the problem by annoying people.

@GregMartin not all people have sexual urges as a result of that. Some people just find it inappropriate and immoral and generally offensive. To do it unintentionally is bad enough. To do it intentionally is bridging on sexual harassment on her part. What about any women she makes uncomfortable, hmmm? Men are not the only one's who can be uncomfortable seeing someone half-naked (in the case of wearing just a skimpy bra or swimwear).

And if the girl says "No, I think it is ok how I dress" you have manoevered yourself in a dead end because you acknowledged that she has the right to do what your problem is. You cannot do anything after that without exposing yourself as a liar. The speech itself is fine, but drop the acknowledgement, it only puts you in an undefendable position.

It seems that most comments here are talking about theory, or right and wrong.  My suggestion involved none of that.  It was purely a practically-minded effort intended to give the OP the highest likelihood of getting the outcome he was looking for.  Almost anyone, when you ask them to help, and they know you know they could easily, will.  Without drama.  I'm not looking to punish her or "teach her a lesson", even though, with a little luck, she will learn something.

@Jeffiekins This is the key word: Almost anyone. And why exactly, if the person has the politeness you are implying, should the person reject your polite proposal because you did not acknowledge that everything is ok? You are gravely mistaken if you think your request will be always correctly understood or that it has the highest probability to succeed. Some cultures and people will take everything you say at face value and the first question they will ask themselves will be: "If everything is ok, what exactly are we doing here?" See Ask, Guess, and Tell Culture.

I thought the problem (the class slows down and people aren't paying enough attention to the lesson) was mentioned explicitly.  So why should she think "everything is ok"?  (And where do I find "Ask, Guess, and Tell Culture"?)  I know it's hard to tell online, so please believe me when I say I'm asking questions, not arguing here.

This is an essay about Ask and Guess culture. It seems that you are more on the side of Guess culture, assuming that she will get the hint about trouble if you make the effort to invite her and tell the problem. Your innocent acknowledgement which you may see as simple appeasement will be seen by someone from an Ask culture as a statement of fact, promised, vowed, signed, countersigned and sealed. A plain "No" is always a valid and used option for an Asker. The results of Guesser and Asker meetings are therefore often terrible.

When I was the head tutor of my college, I had a couple young girls who were barely 18.  They were on my staff and dressed similar to your description (though no bikini's).  Very attractive younger girls who wore very loose tops that... enabled things to be in view when they would bend over to help.  Also wore fairly short shorts, and mini skirts that were slightly too mini.  They also happened to like the see through silk tops.  Though they never came in just a sports bra, they were still fairly distractive to my tutoring center and other students were definitely taking notice.
The situation is slightly different in that they were being employed by the school to be tutors but the distraction still applied.  I took them off to the side one day and told them about how their clothing was not work place appropriate.  This was their first job so I decided to help educate them on what would be work appropriate.  In their case, they didn't realize that the clothing was an issue. Both of these girls liked to dress stylish and why they dressed the way they did.  However, I had to inform them that this style of clothing was not okay for work.
They understood and changed to more professional looking clothing.  Still wearing dresses or skirts but that were not super revealing and more modest.  Totally okay by me.  The damage was already done though because unlike your situation which does not seem to involve aggressive males, my school and in particular my frequent student visitors happen to have a decent amount of military men.  Now don't get me wrong, I have the utmost respect for the military and I mean this in no disrespect to them, simply building the environment for everyone to imagine.
Unfortunately for one, he was a narcissist who also was more than likely dealing from issues with PTSD.  He happened to take a liking to one of the girls and used his predatory nature to harass this girl (mind you this guy was also twice her age and married).
It started out with pet names like calling her beautiful or sweetheart and other things to lure them in with kindness like most predators do, and this made her feel very uncomfortable. He also was following her around acting like "a very friendly guy who wanted to be a part of her group". So She approached me about it and I made a mention to this gentlemen that his words to her are making her uncomfortable and that I understands he is "friends" with her but that she would like it if you didn't follow her around every where she goes.  His excuse was "I am from the south this is the way we talk".  I told him that this was understandable but his word choices and the way he interacts with her is making her uncomfortable and I would like for him to choose other words.  He didn't like being told no and made a big stink about it as well as stating that... "if she didn't like it, she should tell him herself."  Much easier said than done for anyone who is more passive/submissive walking up to someone who is highly aggressive and easily agitated.
It was also during this time, we started documenting incidents in Incident Reports so that if this became elevated, we had documented proof and witnesses because I had a feeling something was going to escalate more.  A few days later, he came by again and went right to the girl who was sitting down at a desk and put his hands on her desk and leered over her demanding that she tells him what I told him to his face.  Pretty much intimidating her when this girl is barely 80 lbs wet (she was actually 86 lbs for the record) and very tiny and he was well over 6 feet tall.  I was not in the room at the time as I was TA'ing for another class but one of our fellow students stepped up to him in which the aggressor threatened to put that student on the ground.  It was at this point, I received a text message about what was going on and excused myself from the class to come in to help settle the situation.  I asked him to leave and when he refused, the librarian (who was a very strong woman and the person who oversaw the tutoring center as my boss) came in and told him he needed to leave.
He then used his narcissist mentality to turn from aggressor to victim and told us he was going to the dean because we are not allowed to kick anyone out or refuse students from entering the tutoring center and he was "just trying to get help for his class work".  After the dean saw reports of the situation and talked to the witnesses, it was decided that this student was no longer allowed to be in the tutoring center while she was working.  She was also escorted around the campus to her classes and TAing blocks by myself and other larger males to make sure he didn't interfere (which there was several times this gentleman tailed us or tried to walk right into me while escorting the girl).  She was also provided security guard escorts as well when ever we needed it.
TL;DR:  Moral of my story, a girl may not realize her dress is not appropriate.  her wearing of yoga pants could be because she intended to go to the gym after class and didn't want to change this particular day.  The see through blouses might be because bras, especially in the summer time, can make the girls get a little hot and uncomfortable and she might have been feeling warmer that day.  You can't assume that she is intending it for attention though it does appear to be this way.  However attention seeking would be done a little more frequent than once or so a month in my experience.  It would be best though to approach her so that she doesn't end up having any aggressive, possessive males try to corner her like I explained in my story.  Unfortunately other people shouldn't dictate how you dress, but some times a level of professionalism, and personal safety need to be considered too.

Thanks for sharing your experience. But there is no real correlation shown in your event that her dress triggered his behaviour. I would argue, with his narcissistic behaviour, he would have done the exact same thing even if the girl was wearing a burqa or a long dress from the very beginning!

I beg to differ.  Half of my staff was female.  Most of them were very attractive younger females.  All who dressed more modestly or professionally.  We also had a very large population of female women at my school due to a nursing program.  There was plenty of attractive younger women walking around but they were all dressed up in scrubs most days.  Point being that she was targeted due to her personality yes, but also because she was pretty revealing and he wanted it.

I do not know more details than what is shared here. You know better. So I am not judging.
but also because she was pretty revealing and he wanted it.
However, this reads more like "victim blaming" to me. Probably it is only me. Let's wait for others' opinions/comments/feedback (as in the form of + votes) than continuing a dialogue. Cheers. :)

I am not victim blaming lol nor have I ever indicated I scolded her or told her "that's what she gets".  please don't make up things for the sake of creating argument.  To put it bluntly the girl hung her boobs out for the whole room to see every time she bent over.  The full view.  When someone with the right mental issues as my guy described above sees a woman who is revealing in such a way and has a very submissive/shy personality, bad things are going to happen.

Using the victim blaming card is no different than someone leaving their garage door up and they have some tools stolen and then saying well just because I left it open doesn't mean you should come in.  While a normal sane person would not want to go snooping around, that doesn't mean you shouldn't take measures to protect yourself.  We live in a world where people exploit the vulnerable.  Self preservation and protection should always be taken into account regardless if it seems "safe" or not.

IMO predatory males tend not to go for the conservative/classy/(whatever is the right term) types.  They tend to go for those who they consider are "easy"  or may be able to intimidate or by other means persuade to do what they want.  Be it accurate or not, to some men, the low cut see everything when you bend over look, does not come across as anything other than showing perhaps low self esteem, and low moral character, hence perhaps an easy target for a large Brutus-esque character to move on (Brutus from Popeye was the image I had of the guy in the original post lol)

Find a female colleague who'd be willing to jointly (with you) and gently discuss with the student the inappropriateness of her clothing choices in an academic environment.
Yes, the student has the right to wear what she likes.  But she's a presumptive adult, and her choices should be adult ones.  Unless she's quite dim, she knows very well that she's behaving inappropriately for the environment, and should be called on her game-playing behavior.  Preferably by a female TA or professor who will be immune to any protestations of innocence.

I didn't downvote, but I don't like this answer because there is a lot of implied sexism in the whole concept of "send a female in to deal with this issue caused by another female". The instructor has to deal with this issue irrespective of the genders involved.

You can always find sexism if you choose to view everything through that lens.  In this case, I would say that choosing to have a female colleague would primarily serve the purpose of reducing the chances that he would have a complaint filed against him, or help him prevail if a complaint was filed against him.

@DepressedDaniel:  the point of having a female colleague is partly, as Itsme2003 points out, to avoid a successful complaint being lodged, and partly because the next move in the dressing-inappropriately-to-wind-up-the-boys game is, when confronted, to feign innocence and perhaps indignation.  The presence of a female authority figure tends to short-circuit that game, leaving the game-player with no move except to feign remorse and try to restart the game elsewhere.

Absolutely: a male person ALWAYS needs a female witness when discussing anything remotely related to gender or sexuality with a female person with less power in the situation than himself. Especially in a university setting, the situation practically begs for accusations of sexual harassment. Even if the meeting ends well, after discussing it with a friend, it's likely she will be convinced that there was a harassing subtext to your talk. Remember that in U.S. universities now male persons are considered guilty until proven innocent when an accusation is made. You need a witness.

I point out an instance of blatant sexism, and what happens? More sexism, which even gets upvoted! Now it's suggested that things must be done in a way that accounts for the accepted fact that women are just itching to make false allegations of harassment.

@DepressedDaniel:  No, Daniel, you imputed sexism, which is quite different.

Some easy solution that missed in the answers: Tell the whole class about clothing etiquette in general without pointing at her as a small excursus on practical professionality. ("Clothing serves more purposes than keeping us warm: It has a communicative function --think of motto shirts. It also conveys a message of respect: Nobel laureates are expected to wear a tailcoat at the ceremony as a sign of gratitude for the honor and respect. Even if there is no written dress code it does not mean that these effects of clothing don't exist. We are still supposed to use common sense. For example, as we don't expect the nearby river to flood the campus during my lecture, we don't appear here in swim suits. As a rule of thumb, dress yourself similar like others in your situation do." -- something like that in your particular teaching style.)
Leave it to her to infere that she may have done something inappropriate. As it is a general lesson, you may also teach it when she is wearing appropriate clothing. You may even do this intentionally to avoid harsh embarrassment for her (of course at the risk that she may not get the point).
Rationale: The students are there to learn something for their future job. But their academic skills will be useless if they can't "sell" them due to their lack of etiquette. As a TA, it's your job to help them in this aspect, too. Not doing this can even be against bona fide.
Note that there are in fact people that are quite smart at their profession but simply don't see their shortcomings in terms of correct clothing, punctuality, table manners etc. This is not malicious. They simply need the help of others, patient teaching, then they'll get it.
I do not encourage fear of harassment accusations. An academic environment needs the freedom of teaching. Rational teaching is never harassment nor crimethink. Don't let the terror in your life. This is not Soviet Union. If you are really afraid of temptation, simply don't invite her to your office but only talk to her if others uninvolved are within sight.
As an academic yourself, you are also free to decide self-responsible how to fulfill your obligation to give the students the academic and soft skills for their career. So you can do this even without asking any superiors. Again, this is not Soviet Union.
As it is only about etiquette, there is no other intervention legally possible. So it's not necessary to involve the department head any more. If she insists on wearing only underwear, it is her freedom to misbehave and she has to bear the gossip on her own. As you will have stated publicly your discomfort with her revealing clothing, this gossip will not concern you.
I once experienced a professor expressing his discomfort to the auditorium about too sloppy emails of some of his students ("Hi" as an opening). This was OK. Some students simply didn't realize that emails are letters (well, technically postcards) and not messages on a web chat. Now they know and it will help them in their future career.

With people showing provocative or manipulative behavior sometimes, the main possibilities are:

ignore their behavior
congratulate them honestly when they display  the behavior you wish, to reinforce this kind of behavior.

I strongly suggest that if you intend to meet the person separately from the class, you do not do that face to face, but with a third person (silent witness), to avoid risks of being accused of... something else.

Heck, if other students are disturbed by this, why don't they address it via the department.  There is a whole lot less that can go wrong for the instructor.  Would especially be helpful if there is another female in the class that could address with the department. (yes, I realize the last statement is actually sexist, in that I am suggesting a female should handle an issue with another female.  But if we look at the world we live in, if a male were to raise the issue, why is he looking at her...same as the OPs situation........I hate the current state of society/culture...one big catch-22)

I am pretty sure she is somehow violating the student code of conduct.  Give that a thorough read.
Also, I am pretty sure that blatant disrespect of the instructor would be grounds for removal from a class at any place of higher learning, so create a dress code for your class, something simple like "no see thru clothing, no swimwear," etc, and email it to your students.  If the behavior continues, drop the student.
Heck you could even add to your syllabus that "This is a college course, not a hangout spot, dress accordingly."
I shall explain this last one:  A professor I am an intern/Lab Assistant for this semester operates in a server lab environment and has had to put up instruction sheets on the walls near each station stating boldly "your mother doesn't live here.  Do not leave any trash." As well as a couple of other statements.
One would ass+u+me that picking up ones garbage would be obvious, and something learned by college, as would be things like putting chairs back when you leave.  This has not been the case.  I see no reason not to add things not to wear to certain courses to these styles of per classroom dress-codes.

So you think that you can prohibit student behavior just by creating a course policy and sending it to the students?  May I ask about your experience in doing this?

"No revealing clothing", what would that include or exclude? It seems very subjective, and it will feel unfair.

@PeteL.Clark  No experience, it was just a suggestion.  And to those upset with the whole dress codes and women being judged by their clothing choices, get over yourselves.  This is a situation where the choice of clothing or lack thereof is creating a situation in which others who are going to a class to learn, are having their ability to learn impacted.  Now, whether or not this is due to the other students inability to ignore said student is another matter.  If someone of any gender pushes things too far, there needs to be some sort of response,

Ah, don't we just love downvotes.  Post a clear concise answer, get downvoted, post something long, drawn out, suggesting ways to go about things to not offend either party or step on anyone toes, and everyone is for it.  @arp  your prompt to remember women being judged by clothing choices is neither needed, and is also condescending, also as I have edited my post to be more specific, your comment is no longer relevant.

As to the "feeling unfair"  Life is not fair.  Nothing in this world is fair.  Know what, I'm 300Lbs+, I should go to class wearing yoga pants, and see if I am not asked to not wear said clothing due to it not being appropriate (not just for my body size, but also not for class due to the form fitting nature......that and because they are for yoga and gym, yet women wear them as everyday pants all the time)

What I am missing here is the situation what the superiors should do to prevent any repercussions if they must fear that protests arise.
In the best of all worlds people would comprehend that behavior diverting attention in a student setting is detrimental and should be avoided. Living in a world which is presumably not the best it is always possible that someone tries to escalate the conflict.
To prevent that they should work out a solution in case it escalates which cannot be regarded as unfair.

One thing is a consistent dresscode for both genders: Opaque torso  and opaque short trousers/skirt. While it allows much freedom to dress, it prevents the worst offenders. It is a pity if only one person is responsible for the introduction of a dress code, but if a rule must be introduced, it must be general. And an university has every right to set up rules for everyone to allow undisturbed teaching.
Another solution (also for other problems) is the right for both professor and students to initiate a secret poll if someone should refrain from a preventable (!) behavior. If the majority agrees, continued behavior will lead to expulsion from the course.

Once a hot topic escalates and interested parties with different viewpoints use it to propagate their agenda, experience shows that trying to discuss it out is a foolish course of action. What most of the time happens is that the actual problem and its development are neglected and the fights are about values (x-ism) centering the topic. As the current discussion already shows, there are many viewpoints and worldviews which are quite convinced that their viewpoint is the only valid one and other people must be not only wrong, but malicious to disagree.

If the last paragraph is true, one can also abolish academia itself. Those discomfort with discussions are free to flee do some dictatorship of their choice or to establish their own dictatorship somewhere else. However, the question what the superiors are expected to do is a good point.

@HorstGrünbusch I have changed the last paragraph to be more precise. Not discussion itself is foolish, it is trying to discuss once the topic got hot and aggravated parties join the protest.

Re: your point 2.: are you kidding?! Institutionalized bullying ... a pretty terrible idea.

@GregMartin First, I am talking about preventable behavior, not something which is outside the influence of the person (race, gender etc.). Given that students are adults, it is quite hard to get a majority for bullying, especially if the poll is recorded and the aggrieved person has therefore evidence if (s)he is not content with the outcome .  Are you more content with the notion that only the professor has full authority about any subjective and contentious issue ? I would be glad to hear what fair alternatives you would propose.

@GregMartin The more I think about the issue, the less I can understand your remark. What kind of picture do you have of students if you think that the majority of them would use this process for bullying ? And who other than the persons involved in something should decide if and what should be done ? Me ? You ? The process of deciding hard decisions in this way is called democracy and if you think it will not work for the university what makes you believe it suddenly works for bigger decisions ?

Short trousers/skirt.   So, I will be able to wear my tactical kilt if I were to choose to eh?

At the risk of stating something you might have considered and rejected, don't talk to her at all, even with another TA / employee who is female deliberately placed as window dressing. Tell HR you are uncomfortable, and ask them to discuss the matter with her. HR is responsible for uncomfortable conversations about social situations, and if you are fortunate, there will be one or more female HR employees who will be chosen for the meeting, thus cutting out the "If a bloke says anything like that it's automatically sexual harassment" subtext.
And as an added benefit, I'd think HR might have the best shot at following up with your school's counseling center. The behavior you mention is suggestive of past sexual abuse and boundary violations, same as the Onion article with a title like "Strong woman overcomes years of childhood abuse to become a successful porn star."

That is highly unlikely. The onion is a fake website AFAIK. The student is likely doing this to be rude and disruptive because she is in some way either attention-seeking or hateful towards the institution. Honestly, this question seems more of an issue of intentional disruption rather than dress code.

The Onion is a satirical news site, along the lines of the tabloids in grocery stores.....only actually humorous.  Personally, I don't see anything to immediately scream past sexual abuse, and we all know what happens when one ass+u+me(s) something.  I would think this is more of a power play on the part of the student.

Regarding the Onion, I know it is a humor periodical, AND I regard it as being, like hacker humor at least sometimes Ha ha, only serious. The article and its sharp humor lose their point completely if the topic is changed to "Strong woman overcomes years of childhood abuse to become a successful [programmer / manager / teamster / librarian]". Much the same is to be said about More U.S. Children Being Diagnosed with Youthful Tendency Disorder, which loses its point if ADD-wave fad diagnoses are taken away.

P.S. I've also been told that there was too much truth in my own humor; this was immediately a reference to YOUR Fast Track to Becoming a Bishop, but it applies just as well to Archdruid of Canterbury Visits Orthodox Patriarch, the joke in the silver rectangle and other entries in Subtle Humor. I am a humorist, of sorts at least, and I regard as naive the assumption that a humor periodical The Onion has no relation to reality.

I think you will find, as I have (the hard way) that the majority of stacks do not take kindly to most humor.

Am I overreacting? If I leave things go on as normal, will my students eventually assume I don’t care? If I have to talk to the student, how is the best way to address the situation considering gender issues?
Answer #1) Yes. You are overreacting. As long is she's not breaking any school rules or the law, she is free to do what she wants to do in a free country. You may not like it, but that's the nature of a free country.
Answer #2) Your students will think thoughts as they so choose because we live in a free country.
Answer #3) DO NOT talk to the student. Talk to your boss who has already said that help will be on the way in a certain circumstance. Don't be foolish. You could get into a hell of a legal bind if you act outside of the rules and/or the law.
Three thoughts occurred to me. Is it possible she's a stripper? Is it possible she's conducting an experiment for which she might have approval? Is she possibly mentally ill?

I cannot imagine an IRB approving a study in which a reasonable outcome is the disruption of a class.

@StrongBad I can't either, but who knows?

@Inquisitive I don't think she has a mental illness: her personality is a bit "plain" or shy, but there are plenty of students like that (including me, I think.) I hardly see a correlation between being a stripper and going scantly clad to class, each context is different. I haven't ruled out this is a "performance"..., but I don't have proofs it is either.

@je_b If she's a stripper, she might not change before coming to class. Also, if she's working a later shift at a club, she might change before class so that she can leave quickly after class. Just a possibility. It may not be probable.

@Inquisitive Read the edit I added to the question. She deliberately undresses for class and not the other way around.

A woman chooses to wear clothing to a class that other people deem inappropriate, and maybe she's mentally ill? That's a pretty offensive assumption.

"because we live in a free country." so which country? Or do you just assume everyone who posts here lives in the US?

@DavidZ Exactly David! I'm glad you could easily gather my meaning! You get an up-vote! I really don't know why others found so much difficulty with that.

@GregMartin when one changes before class and then changes back after class one definitely wonders the purpose behind that. Very suspicious.

@je_b:  "her personality is a bit "plain" or shy"  yet she calls attention to herself by her clothing choices?  That's a really big disconnect!  Women who are uneasy socially (aka "shy") try to avoid attention.

There was some "Deviance and Society" class when I was an undergrad, one assignment of which was to (approximately) "do something you're not supposed to; don't get arrested" and then report back. this seems like it would've satisfied the criteria, and was my first thought when reading the question. But speculation about her motivation doesn't help address the problem.

@JayKominek  Sounds like a sociology class.  In high school, there was a sociology instructor that assigned projects like going to a local mall, and (while in swimming gear) getting in one of the fountains and washing your hair, or another that involved the mall, snorkeling in a fountain.    We can all debate why she dresses the way she does, but no one will know lest one asks her.   Personally, I'd ask a student to ask the student


text:
What to do when your name appears second instead of first?
As a Research Associate I wrote a paper which was published with my professor line manager as second author (even though he didn't work on the paper). I did the research, I wrote the paper, yet his name appears first and mine second in all online repositories such as Google scholar etc. Is this right? What should I do if it is not? Should I be even bothered about this? In the actual paper PDF which can be downloaded my name appears first. It was a good paper as it won an award. But in online repositories my name appears second.

This certainly seems odd. If you go to the website where the paper is listed by the publisher/conference - usually where the DOI leads, if you have one - is the author order there correct with you being shown as first author?

I took away the [tag:plagiarism] tag because it doesn't really describe the situation here.  Anyway, I would be much more inclined to suspect a mistake or bug than foul play.  Hanlon's razor, you know.

@Nate Eldredge Yes I guess you're right, especially since automated citation tools would replicate this error without prejudice. The citation on my professors web page even shows his name first. I'm sure he's not that brash. I'll have a chat with him about it.

@BrianDHall my name shows up first on the main journal content PDF.

@Algorist: Just a thought: some people list their own coauthored publications with their own name first.  (I don't endorse this practice; I'm just pointing out its existence.)  I wonder if that has anything to do with it.

@Pete L. Clark I wasn't aware of that, which could explain his name being first on his web page. However, it's still annoying that he is shown as main author when doing a quick Google search. I'll have a chat with him - it's hopefully just a mistake that's being replicated automatically...

If you're the legitimate first author of the paper, I wouldn't even bother to find out why the error happened in the first place. Instead, my answer focuses on your question of what to do now.
There are two good reasons why you should insist on a correct authorship record: (i) First authorship of a (good) paper is a valuable asset. (ii) So are citations of your paper. With inconsistent information in the repositories and the paper itself, citation counting tools like that of Google Scholar might not index all of its citations. Keeping that in mind,

the most important party to contact is the publisher of the paper, since these people maintain the official record. In particular, they distribute the meta-data of their publications to other repositories. I can't tell if they will actually distribute individual error-fixes as well, as would be the most convenient option in your case. Still, they can correct the faulty data in their own repository, which will strengthen your case when you contact other parties.
Some databases/repositories, like DBLP, allow you to submit error reports individually. You can google for "(name_of_database) error report" or just look on the respective database's website to find details.
With Google Scholar, the situation is a bit more tedious, since they do not provide a process to submit error reports. Information usually gets checked and updated automatically after some months; there is nothing you can do to trigger this process. The thing you can do is to create a new, corrected entry for the paper in your profile. Then you can "merge" it with the existing entry, so that citations of the paper with its current authorship information are counted.

According to this: http://www.harzing.com/popbook/ch2_4_3.htm you can supposedly report an error to Google Scholar. Never tried it myself, but the links therein might be useful for your answer. +1 anyway!

Thanks. I will do all of the above, and still speak to the professor.

@BrianDHall Thanks! But the link on that website goes to a generic contact form. Actually, using this form for error reports seems to contradict the course of action suggested by Google Scholar itself (in essence, "tell the webmasters of the source website to fix it and wait 6-9 months").

@lighthousekeeper Haha, "appropriately irritated" - that's actually a really good link, and it seems you are quite right. I think I'd accept your source, from the horse's mouth, over the contact form I suggested too :)

Feedback regarding the Google Scholar Report Form: a few months ago, a paper of mine appeared under another researcher's Google Scholar profile (similar names). I manually added the paper to my profile, and then used the contact form mentioned by Brian. A few weeks later, the issue was solved. Of course, I don't know if someone at Google took a look at my report and solved the issue, or if it was automatically fixed.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

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text:
How to get students to use the course forum?
Forums are common features of online courses. The software is usually provided by the institution. It is in everyone's interest to make a course forum useful, maybe even lively; generally we want more posts rather than fewer, and more interaction between those posts, rather than a bunch of individual observations.
Using the forum is sometimes counted as part of students' grades. There are a great number of ways of measuring participation, though; I previously asked How to score class participation, correcting for natural outspokenness?
That said, making forum activity part of student grades is not necessarily key to making the forum useful. What is the most effective and practical way of getting students to post in the forum?

What is your reason for wanting students to post more in the forum? I'm not very familiar with online courses, but in ordinary courses, it is my experience that forums in VLEs are somewhat superficial.

@101010111100, using the forum means more engagement with the material and cross-fertilization of ideas between students. They're not perfect but they're a major communication channel, built for threaded discussions rather than, say, announcements.

I think the key to a forum being somewhat lively, at least from my experience, is a blend of the following:

There needs to be instructor/TA participation in the forum itself. This is both a boost to the "signal" of the forum.
Incentivize interaction not just posting. If you're requiring forum posting, require not only an original post, but also one or more replies to existing posts.
Start broader topics early and help keep them running. Many forums are organized by chapter, assignment, etc. which kills any participation (even if you have it) the moment people click 'Submit' on the assignment.

That being said, I cannot yet think of an instance where I was actively glad to have the forums for an online class.

I want to add a caution to the first item: my limited experience (and the consistent advice I've gotten from specialists) is that one has to be careful not to have too much instructor/TA involvement (especially responding rather than starting discussions) because it can turn it into a lot of dialogs rather than having students interacting with students

@Henry I agree, though my experience is that without some involvement, it's students interacting with no one.

Your suggestion of broad, long-running topics is a very good one.

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text:
The potential advisor suddenly stopped answering my emails. What should I do now?
Sorry for yet another 'professor does not respond my email' question. I searched through other similar questions, however their context was slightly different from mine.
I am a M.Sc. graduated from Asia looking for a PhD position abroad (i.e. Canada).
About the 9th of December, I sent an email to a professor in one of the Canadian universities, asking to join his research group as PhD student. He initially found my CV and transcripts interesting and requested for some recommendations letters being sent to him.
It lasted until the 21th of December when all of my references finally sent their recommendation to the professor and then I notified him about it,  however I didn't receive any response from him.
Because of the new year holidays, I found the delay normal and I waited until 7th of January (a week ago) and still no response! Then, I sent another email to him, politely asked about the status of my application and recommendations which have been sent to him and he has not answered this email too.
The professor was really positive in our initial contact, so I don't know if I should consider this type of ignorance as a rejection and move on or I need to make other decisions. Actually, I am also interested in research of one of his colleagues and If I knew his final decision about my application I could start talking to the other faculties before the deadline pass.
P.S: In this university, the admission decision is completely based on finding an advisor willing to support your research through your graduate study.

Update: I sent another reminder email to him after a couple of weeks, politely requested for a feedback if he received my email. I used email tracker software and I found he opened my email and still no answer.

Please also consider the possibility that PI's proposal gets rejected and there is no more funding to support any Phd, although in which case it'd be more considerate of him/her to notify you of this bad news.

There isn't a single faculty member, myself included, that I've spoken to recently that isn't overwhelmed in January.

Around here a lot of people don't work in the first week of the year. And then they come back and have to get back into everything. Let him make the decision and the necessary planning in peace. I was actually on holiday until yesterday, others might do that too. My boss last year was on a conference during the second week of the year. There are many options.

At some universities, there is a quiet period between the application submission deadline and the first round of interviews, during which faculty and applicant communication is discouraged.
As faculty, I've found such quiet periods annoying but understand the rationale which is to level the playing field by suppressing off-channel communications with a secondary purpose of limiting too much badgering on the part of applicants.
Or the professor could be skiing or preparing for the new semester. Either way, I'd hesitate to badger too much.
update: If I found a prospective student used an email tracking program on me, I'd drop them from consideration immediately. See: Is it rude to use tracking softwares for the emails that you send to potential advisors?

Is that quiet period really meant to work out in such a way that the advisor acts as if they had suddenly disappeared from the face of the Earth, without any minimal information to the applicant that the application is being processed and the next contact will be established by the university, but possibly only after a few weeks/months?

Graduate admissions are on the bottom rung of priorities right around now; it's the interview season, so most faculty members are holding interviews and attending meetings. They are also reading files for postdoc applications and going to hiring committee meetings. I'd wait a couple of weeks from now, and just move on and contact your second choice at the university. If your first choice advisor gets back to you much later, you could either resume contact (and tell him/her that you've also been taking to his colleague) or politely decline by saying that you assumed rejection and move onto your second option, if you've changed your mind and already committed to some other option.
Although it might be slightly awkward to be in touch with several labs at one institution, nothing is preventing you from contacting other institutions, so make sure that you have a backup as well.

In my opinion, send him a follow up email the second time and wait for a couple of weeks for reply. He may be busy or forgetful, anyhow if he don't reply it after a couple of weeks, consider yourself rejected.

Or he is still traveling (skiing?). Depends when the winter holidays end.

@CaptainEmacs You can never really tell what may be occupying their time. I knew someone who worked closely with an academic who also had a sheep farm, and who would be completely incommunicado for several weeks during lambing season.

@Captain Emacs:  And when the winter break ends, the instructor is likely to be pretty busy with beginning-of-term chores.

Not sure of how canadians do their winter breaks, but here in the USA, most teachers are unlikely to check their emails after a certain period in a class break.  Usually, they will reply to emails within a few days after final grades have been posted for any questions or discussions needed but after that, take the 2 weeks just like any other student.  Some teachers will reply and usually they will state this closing in on the end of class stating that they will be available for emails throughout the whole break.  Unfortunately for you, you weren't in any classes being taught, and he didn't communicate that he will not be replying any time soon.
You did email him later on after the break period but you also have to remember that is also when teachers are preparing for the new semester, getting emails from new students, going through all their emails that were left from the previous class and so on.  I wouldn't lose hope.  See if there is someone else you can contact that may also know about the status of the application or even someone else from that group you can try to contact.  At the very least, persistence shows you actually want to be a part of the team and putting in the effort to show you are serious.  This could help you win the spot over someone who may be more qualified, but did little to show they are really interested in the position.
Contacting others who might end up being a part of that decision could play in your favor (as long as you don't come of annoying!).  As other people said, things take time and it is annoying some times, especially when they reply quickly getting all the information they need and then leave you in the dark.


text:
What can I do if my academic references are not responsive?
I provided references of two Professors from my previous University. I talked to them before supplying the references.
I believe, the universities sent some Emails asking them for some kind of confidential report. They are procrastinating responding to the Emails from the universities I applied to.
They are not even responding to my calls and mails:

I contacted them last week of December to let them know about the reference.
Sent SMS text on 11th January after I had submitted the application.
I also sent them personal Emails on 15th January.
Called them on 18th January.

I believe the last date is 31st January.
How can I get around problems like this in future?
Is there any formal way to submit applications without references?

By "supplying references" I assume you mean you "asked them to write you a letter of recommendation." By teachers, do you mean professors? Or are these teachers from a high school? Or teaching assistants? How much time have you given them? When are the deadlines? You said you talked to them - I'm assuming they agreed to write reference letters?

I don't want to be rude, but I asked several clarifying questions and you only answered the last one. All of the questions I asked are pertinent to even attempting to answer your question or give some suggestions.

"Respond to emails" could mean almost anything. They could be automated emails asking them to submit a reference electronically or by mail. They could be emails asking "Did you work with anonymous? Could you verify ____ about them?" They could be emails asking for a more informal assessment "What do you think of anonymous?" My other questions, which you gave no information about, are still unanswered. Frankly, if this is typical of the way you ask for help from people, now editing your comment to say what I "missed," that might explain why you aren't getting any response.

The general script is: ask for letters with the prospective due dates, preferably a month in advance of needing them; send an email to let them know they should be getting an email from the program that requests them to upload the letter; send a reminder email 3-5 days before the due date (assuming more than a week has passed since your last email); if not received yet then send them a reminder email the day before/of the deadline with the time due; if the deadline has passed, or you have some reason to think they aren't going to do what they said, get additional help. Where are you in this?

@BrianDHall, I contacted them last week of December to let them know about the reference. Sent SMS text on 11th January after I had submitted the application. Called them on 18th January. I believe the last date is 31st January.

@BrianDHall, I also sent them personal Emails on 15th January.

Echoing BrianDHall's timeline, you should be patient, and please stop pestering your references. If you still haven't heard from them by the end of next week, send them another, polite email that simply reminds them of the deadline.

Also see this previous question which might help you.

The deadline for letter submission is 31 January? What's the problem? They still have more than 10 days to submit.

Not an answer to your question, but read this: http://ksuweb.kennesaw.edu/faculty/rbrow211/recommendations/index.html  You might send an "I thought this might help" email with the info listed to your referees.  You do not need a FERPA release, but read and heed my advice about waiver of right to access.

Oh, I think the issue might be that you expected things to be turned in well before the published deadline - which is not generally how most people behave in, well, any situation. I think the earliest I had any reference letter turned in was about 4 days before my earliest deadline, and the latest was about 30 minutes before the posted deadline. Sounds like they are doing ok, but how useful call/text is will vary by the professor, and would only really make sense if you know that this is actually useful to them. It's quite natural to feel panicked with things out of your control like this.


text:
Is it appropriate to give a gift to a teaching assistant for helping outside of work time?
I am thinking of buying a small gift, like coffee, for a teaching assistant, who helped me solve problems in a particular subject, even outside of work time, to thank for the effort.
Is this appropriate or even allowed?

Questions like this are affected much more by your local culture than by any global academic conventions.  I think you should ask someone closer to home.

Don't do this if there's any chance that the TA will be marking any of your summative assessments.

I think this question should be clarified. Upon reading it, I had the distinct impression this was a professor (boss) asking about giving a gift to a "subordinate" for helping them outside of working time. It was not until reading the comment by @DavidWallace that I realized it could also be the other way round, a student thanking their "superior". Answers might change somewhat based upon that knowledge.

Vote to close as "unclear what you're asking".(I agree with @O.R.Mapper)

Where are you talking about?

I think it depends on how much they went above and beyond what was expected. I once tutored a student on the weekend (about 5 hours) for three lectures they would miss because they were taking the final exam early and going out of town. I was under no obligation to do this. I got a box of cookies and a card AFTER the exams had been graded for my trouble and I really appreciated it. As a teaching assistant, most students never acknowledge or care about the hard work I put in to make them successful.

I would consider that, in many cases, helping students "outside of work time" is often still under the normal job description of a teaching assistant. However, since you are asking the question, I am going to assume that your TA went above and beyond their normal calling. Even in that case, a gift might make someone uncomfortable, and should certainly never be given before grades are final.
Other options that might achieve what you want without making anyone uncomfortable and that might have greater impact with no more effort from you than a gift could include:

Nomination for a teaching award. Many institutions have some formal mechanism for recognizing great teaching assistants; even a nomination could be something that TA could use in the future on a job application.
Letting the professor know how helpful your TA was. Professors don't see all aspects of their TA's work. Knowing that a particular TA was helpful to the students might help that TA get a future position, or is material that can be included a letter of recommendation. You could also ask the professor if there is anyone else in the department where you can send compliments for a particular TA.

There is also nothing wrong with thanking your TA directly and making it clear their time was appreciated - no need to go overboard, just a simple email is sufficient.

+1 for methods of acknowledgement which can positively impact his future career.  I'd rather have a glowing recommendation than a gift basket any day.  (Though I wouldn't mind both.)  ;)

I'd also like to add that in TA training at my US university all TA's are strictly told not to accept gifts from students. I would freak out if a student were to try and give me a gift.

I would suggest writing them a note or card letting them know how much you appreciated their help; a couple of have students have done this for me in the past, and I've been really tickled by it.  It scratches the same itch as a gift, but doesn't require figuring out what they would like.  I wouldn't have minded getting chocolate instead, but it would have felt a little stranger.
To expand on something Bryan Krause said above: even if there's no obvious mechanism to nominate them for an award, you can tell them if they need a letter from a student in the future (these are standard for teaching awards and tenure applications, though oddly not job applications), you would be happy to write one.  That both expresses your appreciation and could be useful to them.

If you want a touching and appropriate gift, I suggest sending a personal thank you message to all teachers that helped you when you finish your studies. Just beware not appearing just like trying to network.

Do beware of regulations at your particular University - At my institution it is forbidden as a TA to receive gifts or payment for TA work from students.
I think it is designed to stop us using our TA positions to make extra money from students for additional tuition but it covers literally anything. I had a student keep offering to buy myself and a colleague for helping him outside lab hours - took a lot of explaining that we would help but couldn't accept any form of payment.

Who are you?
If you are someone higher up in your department and a TA stayed behind after running one of your labs to help you with something then I don't think anyone would object to you buying them a drink. At least where I am staff buy drinks for their peers and subordinates all the time.
OTOH if you are a student buying stuff is likely to be awkward at best (and may sometimes be officially forbidden). There will be the lingering question of whether you are trying to bribe the staff member to give you better grades.

There is a philosophical aspect which can added, and that is related to the will and worldview of the student offering the gift. Whether a gift is appropriate can only be fully known relative to the student's will and worldview.  If the student has dis-associated themselves from intervening institutional concerns (whatever they may be in terms of things such as "policy" and "superiors") and is able to act freely of themselves, then the appropriateness of a gift would seem to be based exclusively inside their own determination.  And due to this being based internally, only the student will be able to answer for whether such a gift is appropriate or inappropriate.

Totally fine as long as the gift itself is appropriate.   If it is something small that just says "Thanks", then I'm sure they will appreciate it.  Just be careful not to give the wrong impression with a gift like chocolate.  Many would consider that a romantic gift.   Gift cards are good.  $10 - $20 to Starbucks is my go to for this type of thing.

I gave chocolate as a gift to a collegue just this week for a small favor he did for me. It's just normal here. Flowers would be regarded as a romantic gift though. Customs are different everywhere.

Make sure it is after the course is over and grades have already been submitted, so it doesn't appear like a bribe.


text:
Combining mathematics and physiology?
I am currently studying Mathematics as a undergraduate, but I'm also very interested in Physiology. I was also recently accepted to an Applied Mathematics master's program.
Is there a field of research in physiology/pharmacology that admits, or even encourages mathematicians with a decent knowledge of physiology?
I've found that there are a few undergraduate math modules named "Mathematical physiology/biology"; this is sort of the reason for this question. There are also books upon books on the field of mathematical physiology, which makes sense as in many cases it seems like rates of change are important (glycolysis, etc).
This seems like a radical change in subject, but perhaps someone who has been through the rigor can shine light on this.

I made some edits to the question and modified the title to attract more attention. Feel free to edit back if you think I changed something significant!

Typically, you will be better off studying mathematics with additional knowledge in X rather than a studying X with additional mathematics. Why? Because you can always enter X as a mathematician, they will welcome you with that. At least for academic jobs.
Talking about mathematical biology: it is mostly mathematicians who do biology rather than the other way around. Granted, you will also find physicists and computer scientists there.
A friend of mine claimed that the members of mathematical biology groups get their biology from Wikipedia and then apply their mathematics to it, most of which is settled in analysis of PDE and numerical analysis. He certainly exaggerated a bit, but there is truth in that statement.
Hence my recommendation: if these topic interest you, then pick a math graduate school that feature collaboration with math biology/physiology.

Brilliant. This is what I was looking for. Thanks :)

Great answer.  But make sure you don't limit your knowledge of the field of application.  Do take some courses in that field, if only to develop your intuition.


text:
How to compose mathematical papers in engineering conferences?
I'm just preparing a paper in an engineering context about a new mathematical framework to do something novel. I've something around 9 definitions, 2 lemmas and 1 theorem (in addition to some remarks for further explanations). Currently, these items are successively placed in the manuscript, in that there is nothing between each pair in view of extra explanations (except those sparse mentioned remarks), like this:

Def. 1
Def. 2
Def. 3
Rem. 1
Def. 4
Def. 5
Def. 6
Def. 7
Lem. 1
Rem. 2
Def. 8
Lem. 2
Rem. 3
Thm.

In one hand, some people around me say that such roster of mathematical stuffs without extra illustrations between each pair of items is incredibly tedious for the reader, because the paper is supposed to be an engineering one.
On the other hand, I've faced with a 6-page limitation for this manuscript and can not elaborate the stuffs, considerably, without violating the restriction. Furthermore, I've done my best to apply the necessary explanations as much as possible by considered remarks. But there are still situations in which 3 or 4 definitions are located at the paper next to each other.
Is this a poorly-organized fashion of proceeding-paper composition (especially in technical fields, not pure mathematics)?
Any idea for better arrangement?

Let us continue this discussion in chat.

Yes, it is considered good form, in mathematics, to have at least a sentence to introduce 'named' theorems, lemmas and definitions and navigate the reader through the results. And an "introduction" section --- you can dispense with the conclusions.
Sometimes in this kind of venues you are allowed to put the proofs of your theorems and lemmas in an appendix (which doesn't count against your page limit). Ask the organizers if it is the case.
If not, then leave everything as it is; it seems that you have no better solution (assuming that you have already tried to save as much vertical space as you can).

Usually, at least for the engineering conferences I'm used to, an appendix counts in the page limit. Though in mathematics the structure outlined by the OP could be considered good form, with some linking text, the main issue is that an engineering audience and the reviewers might find it not appealing or not suited for the conference scope.