What I can sell to make money in high school?

DIY clothing is very popular. Do you know how to sew? A lot of teenagers sell shirts, pants, beanies that they made, both from scratch or just modified. I knew a girl at my school who used to make things out of duck tape like bookbags and other things and sell them. A cool site that gives step-by-step instructions how to make things is instructables.com. I bet you could find something quick and simple on there that you could make and sell. If you make the things you sell instead of just selling things like energy drinks that they could just get at the store, you will sell more and make more of a profit. You can buy the supplies to make things for way cheap and sell them for lots more. You just got to find out what kinds of things people are interested in. It's all supply and demand.