Physics Teacher: Let's talk about apparent weight versus real weight. On a roller-coaster, which one changes?
Student: Apparent weight.
Other student: Unless you throw up.

Physics Teacher: (sings) It's so fun to mumble to your neighbor. {stops singing) Why am I singing?

Physics Teacher: There's time to get your tests back if we're done reviewing.
Student: There's time, we're done.
Teacher: We're not done!
Student: (yells) Yeah, we are!!!
(stunned silence)
Student: Sorry, that was rude.

History Teacher: By the 1920s, the Klu-Klux Klan doesn't discriminate. They don't just hate black people any more. They hate black people, immigrants, Catholics, femininsts, socialists... They're equal opportunity haters.

Spanish Teacher: If I wake up at three in the morning every day, what am I doing wrong? Going to bed too early?
Student, sort-of quietly: Or you're just crazy.
Teacher: What?
Student: Nothing!

Spanish Teacher: I never called your class dumb. I called you bottom-feeders, I didn't call you guys dumb.

In math class:
Student #1, to Student # 2: You make this class durable. Not durable, what's the word I'm looking for?
(they discuss it, trying to remember. for several minutes)
Student #2: I'm thinking manageable, but that's not right...
Other Student: Endurable.
Student #1: Right, that's it. Thanks.