Difference between 那时，那时候，当时，那会儿，那阵子 I was trying to say &quot;at that time I started to be interested in maths&quot;. I translated it as:

当时我开始对数学感兴趣.

Then I saw some other expressions to say &quot;at that time&quot;: 那时，那时候，那会儿，那阵子.
What are the differences between those? I suppose 那会儿 is &quot;at that moment&quot; instead of &quot;at that time&quot; but what is the difference with 那时 and 那时候? And what is the meaning of 那阵子?
Thanks.
那时/那时候 - formal, a long period of time. Whichever one you choose depends on how fast-paced you want your narration. 那时，我开始对数学感兴趣 makes the most sense because your growing interest in math sounds like a long-term process.
当时 - formal, a very short period of time. Example: 当时，我吓坏了。
那会儿 - colloquial, any length of time. Example: 那会儿，我在火车上只吃方便面。
那阵子 - colloquial, a very long period of time. Example: 那阵子，我特别无聊。