I buy several packs of notecards at the beginning of the term. I pass them out at the beginning of the class. At the end of the class, I will ask the student to take 1 minute and write the important things they learned. Or I will ask them to write suggestions for the material. Sometimes I give them a particular thing we discussed in class and ask the students to tell me everything they know about that thing. The students never know what the questions will be, so I think that keeps them sharp during class. It is very helpful to me to assess my performance during class.