when the classroom does strange things to adult learners

I've been having weekly French lessons for the past few months at the adult education centre (thanks L for finding them for me despite you being the other side of the country) and today I realised that despite everyone in the class ranging from 20 - 35 years old, the classroom brings out the inner child in most people.

OK, we sit around, listen to the instructor, do our exercises like in a school, but when we have a question we get to call out to the instructor by her first name, and there's no hand in the air. But, I witnessed such a typical classroom situation today - people started getting competitive when answering questions on a comprehension exercise. I mean, when the instructor asked us if we needed to hear the CD again, one girl shouted out 'Well, I've answered them all' and put her pen down. Ha! Then when we were going through the correction, people started shouting out their answers, trying to be louder than the next! And funniest of all, the girl who sat next to me actually did the clenched fist thing with the simultaneous 'ouuuui' when she got a particularly difficult question correct. Come on guys, I thought we had gone through and come out of this behaviour at school?!
It's strange what the classroom brings out in people, even those who have all their wisdom teeth, a mortgage and probably children.