Question

what should be my reaction as student when i know about the theft of money in my classroom. how should write this

Answer 1

You shouldn't be just running out of the class shouting.Very calmly,you must observe what he was actually trying to do since many a times, it happens that you see something which is not true.May be he was just trying to see something and you found him in such a situation that it appeared to you as if he was stealing something.
But if it's for sure that he indeed is trying to steal something,then you must report about it to the appropriate authority of the school.

Answer 2

You should politely and intelligently handle this situation. You should try to discover the person who had stolen the money and if you are not able to do so then also, you should explain the whole situation to the teachers as this might be helpful as the school authority then can take some actions against steeling either money or any other stuff. As steeling is a big and a wrong thing so this should be in the notice of teachers.