Students forget what they learn in class

Inside Higher Ed, source of many interesting articles, recently had an article called Memory and Sequence about how students usually forget what they learn in class.

I often hear professors complaining that students don't know the material they should have learned in the pre-requisite class.  They may blame the students for not being smart enough or studious enough.  If they did  not teach the pre-requisite class themselves, they may blame the instructor of the pre-requisite class.

But it seems to be a systemic problem.  Instead of casting blame on individuals, maybe we can try to understand why it occurs, and how to overcome it.  As the article points out, students forget things when they don't practice them.  A class I took a few years ago had several exams over the course of the semester. As I reviewed for an exam, I realized that I no longer remembered that things I had learned three weeks previously.  I appreciated having the exam, because it forced me to remind myself of those things I had forgotten.  Sometimes courses test the material learned in one unit, then move on to the next unit and test the material in that unit, and never again ask about the material learned in the first unit.  It is less work for professors to write fewer and shorter exams and to grade fewer and shorter exams, and professors also experience less resistance from the students that way, but I think it is a disservice to the students not to force them to review by giving cumulative exams.  And it doesn't just have to be about exams.  Instructors can be creative in coming up with ways to get students to refresh their knowledge of material previously covered.  Studies have shown that students who review their notes after class retain the material better than students who do not.  We need to instill such practices in our students.  I think that part of doing that is reasonable workloads.  When I don't even have enough time to read the all the required material once, I will not leave some material unread in favor of reviewing material I have already read.