In this scene this is the math teacher. The math teacher is confused and annoyed because no one is answering his math problems.
Why are you guys not talking
In this scene the music teacher is having almost the same problems the kids are not practicing for their concert.
Come on sing!!!!!
Even the kids are not talking after school that they most of the times do. They are just going home quietly. The reason why the kids are not talking is because they are doing a no talking contest boys vs girls