K.M.
I would get a gift for all of the teachers she has spent time with. You don't have to spend much though. Here is a good idea that is cheap! Get a 2 liter of coke and tie a bag of microwave popcorn to it. Attach a note that says "Pop! Pop! Fizz, Fizz! What a great teacher you is!" I don't see anything wrong with getting something special for the teachers she spends the most time with. Good Luck!