Back to school

Reading session this morning with 5 years old kids.
Four groups, one very unruly...
Usually I read in the school library witch was busy today, so we were in an empty classroom.
I felt uncomfortable as my life in school lets me not so good memories.
One of the girls was reading very well, so I took her as an assistant, the other ones were admirative "You can read?"

I need a little help from my bilingual friends, can you translate for me the funny reactions of some of them:
"Oh, tu as changé de cheveux! pourquoi ils sont en petard?"