What is the easiest possible way to start teaching children how to play chess? As a followup to What is the earliest possible age to start teaching children how to play chess?, I'm wondering: What is the easiest possible way to start teaching children how to play chess?  The point is that at such an early age, it's possible, if not likely, that the best way to teach an adult would not apply to a young child. Any suggestions?
The easiest way depends on age.

If they are really young, just start simple with how a plain board and introduce the pieces one by one (where they go on the board and how they move). Then put all the pieces on the board and show how the pieces move together.

If they are a little older, I would play show them short games with tactical ideas and mating patterns.  No need to dwell too much on the opening yet or the endgame.  Stick to the fundamentals first and make sure they have a firm grasp on that.

You probably will also find some tips on http://www.chesskid.com and http://www.chesskids.com