Getting summer school from mom

It's summertime & your mom is preparing your next school lesson. It's very hot in the house, and mom is bent over at the computer, wearing only a shirt & thong. You walk into the living room, see her bare ass & your cock gets hard. She doesn't notice you at first and by the time she turns around, you have a raging hard-on. She realizes that you don't know what's going on with your own body & decides that this can be your next lesson.