Um... I'm... staying at home.
I'm hanging with my friends/family.
I'm writing my Student Council/PTA President speech.
You shoot your arm up immediately.
You know the answer, but don't raise your hand. Somebody else will know the answer.
You are not sure the answer. Hopefully someone else will.
Respond in a detailed, correct answer. You might as well.
Weren't really paying attention. Maybe you can guess.
Say the answer very quickly to get the attention over with.
Go home, do your homework, and read.
Go straight to sports practice. I can't be late!
Go to music lessons/drama class/dance lessons and then begin your homework.