While teaching economics, this is a fantastic culminating project for the students! They will make a good or perform a service for a store. Parents love being invited to this and have a fantastic time. We are an IB school, so it's great to watch kids learning and discussing what they've learned in econ.
After the activity, I have students write a reflection paragraph to let me know what their income gained, if they had opportunity cost, and if there's anything they would have done differently (advertised, created special sales, etc).