If most students comment that the course was too fast, a natural idea is to slow it down. If most students comment that the course was too slow, a natural idea is to speed it up. But what if half the students think the speed was too fast and half that the speed was too slow? A frequent reaction to such a situation is to conclude that the speed was just right and not change the speed the next time, but this may not be the right reaction: under the same speed, half of the students will struggle and may fail. A better reaction is to provide additional help to struggling students, e.g., in the form of extra practice assignments. How can we do it without adding more work to instructors – who are usually already overworked? A natural idea is to explicitly make some assignments required only for those who did not do well on the last test or quiz – this way, good students will have fewer required tasks and thus, we can keep the same amount of grading.