Your straight A's student stepsister is a good girl. Complete opposite of you really. You are a partyboy but now you need serious help with math homework so you ask her for help. She is busy with her own stuff but promises to help you. You just happen to see her nice ass so you feel her up and she is not happy. But she knows how to motivate you. If you get homework correct, she'll take her clothes off for you. Now you have to actually try your best. How far will this homework help go? One thing for sure is that at the end, your stepsister may not be such a good girl anymore.