In EMR16 and Stat139, students periodically do very brief "mini-assignments" which require them to submit or consider something that the instructor incorporates into lecture.
For example, one mini-assignment involves finding a plot of data on the internet. Students email their plot to the class gmail account. Professor Cassandra Pattanayak then starts almost every class discussing a relevant plot that was submitted, being sure to thank the contributor. In another example, students had to find a news article claiming causation. Students were asked to observe what words were used and determine whether such causal language is justified. They then had to email the link to the article and a sentence describing and evaluating the causal language. The following class began with a corresponding discussion.
Here is the description from the syllabus:
Mini-assignments (5%). Occasionally throughout the semester, we will ask you to complete very brief assignments, to be submitted to the class gmail account. The mini-assignments will be graded pass/fail. You will not receive credit for late miniassignments, but two mini-assignments will be dropped.