Mattress Throwing - a new Olympic sport?

Tessa has gotten into a really bad habit at daycare.  She is strong enough to lift and throw her mattress out of the crib at daycare.  If that wasn't bad enough, she has taught two of the younger girls at daycare to do the same.  I am working with her daycare providers to brainstorm a way to attached the mattress so that she can no longer throw it out of the bed.  The mattress at home is too heavy and tight fitting for her to even attempt to give it the ol' heave ho.  Too bad that didn't stop her from trying to toss the mattress out of the crib at my parents.  Below is the result of her efforts.