Funny shot! I think a more realistic looking classroom environment would help for me (mostly I don't like the background - chalkboard or whiteboard would be better). The vignette is a bit too much for me as well.
My science teacher in 9th grade didn't looks like this. She had hairy legs like a man and insisted on wearing skirts. Uck.
Aside from the pretty girl with excellent cleavage, this is a decent studio shot. The bits and pieces on the left side are borderline clutter, but are needed to make the challenge, I think. I think this is a good idea, but it is the beginning of an idea and still had room for refinement.