Testing the teacher

You sit down at your desk after giving back the girl her top. After a few minutes of taking notes, you decide to test out one of your fetishes on the teacher. You look up at her and see her standing at the front, facing the white board. She's wearing a shorter skirt than usual, so you'll probably see the changes early on.

You look at her rear end, and focus on making her butt bigger. For the first few minutes, nothing happens. You let out a small sigh and think "I wish that her butt had grown some", before looking down at your paper again. But right before you look at the paper, you notice something. The teacher's butt is ever so slightly growing. You stare in bewilderment as you watch her flat ass change into a nice pair of rounds bumps. You smile a little, thinking about all the possibilities you have with this power.

You sit there for a few seconds and decide to...