The minute paper

Implement the minute paper, which works by letting students know that they will be asked to write a short summary of the lesson up to a certain point to write up about lessons they have derived from the lecture. Announce at the beginning of the lecture that you will interrupt your class halfway through the period so that the students may write a one-minute paper on a topic derived from the lecture or that you will ask them at the end of the lecture to write the most important thing they have learned.

Source:
McKeachie’s Teaching Tips: Strategies, Research, and Theory for College and University Teachers
Svinicki, M, McKeachie, WJ, 2011