Well, I reckon that will teach her to misbehave in class. Good theme. 🙂
I might work on the size of the feet in relation to the person tickling them though. I realize you are trying to use perspective, but the foot doesn't need to be that big nor does her head. In fact, to counter this and make it look as it should, simply draw her head smaller, since it's the farthest thing away, and then make things progressively bigger, with the tickler being the biggest since she/he is in the front.
Unless of course theres a reason you drew it this way. In that case you don't need to change anything.
Either way its a good job.