Learning by doing.

You have roughly 40 contact hours in a typical course. If all you do in them is lecture, you might as well just hand out your notes and let the students find something more productive to do with all that time. The only way a skill is developed—skiing, cooking, writing, critical thinking, or solving thermodynamics problems—is practice: trying something, seeing how well or poorly it works, reflecting on how to do it differently, then trying it again and seeing if it works better. Why not help students develop some skills during those contact hours by giving them some practice in the tasks they’ll later be asked to perform on assignments and tests?