Here is a Cultural Literacy worksheet on the concept of a mixed economy. It’s a full-page worksheet with four questions, but it can–and very easily, because it is a Microsoft Word Document–be expanded or contracted depending on how much you need students to know about the subject. It’s decent general introduction, but it does presuppose some knowledge of the difference between market and command economies, and private and public enterprises.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.