Straight A Student Fucktation

You just got home from school and step mommy comes to greet you. She's so excited, you have straight A's. She wants to reward you with something you've always wanted. To finally fuck her! She climbs on top of your cock and rides you but reminds you not to cum. She wants you to last a while in her. You can't hold it, you finally cum! She tells you that this will continue if you keep up the good grades.