Tarantulas aren't exactly silkworms.

Scenario: Kid keeps T under bed without parents knowing. (Is how how I kept my snakes as a child, so it happens).
Kid gets bitten, or some kid has an a reaction to the urticating hairs and you have loads of trouble, and that kind of exposure can't be a good thing for the hobby.

Not saying your idea is faulty, but perhaps consider pulling it off in a more responsible way? Have a talk in the biology class, have parents sign disclaimer/permission forms, have the teacher do follow ups. That kind of thing?