Nervously scratching her b giggling on their way home from the beach on the river:

'Tu veux qui en maths, Mr machin?
- Oh non, il est trop nul!
- Et en français, Mr truc?
- Oh non, il est trop con!

Etc etc...
I'm sorry I can't translate the universal language of our pre- teens, may be La Mammarazza could help me, but I find this gesture quite eloquent!

Start of the school year tomorrow!