The Forgetting Curve

The Forgetting Curve is a model that describes how information is lost over time when there is no attempt to retain it. It originated in the late 19th century with German psychologist Hermann Ebbinghaus.

The graph above published in this article in Quartz shows the forgetting curve is initially very steep, but Ebbinghaus found that the amount of learning retained eventually leveled off. So the next day, he might remember just a few bits of the new information but he would remember those bits for many days.

Ebbinghaus also found that the curve of forgetting could be interrupted by spaced repetition. This graph published in this article in Medium shows that when the new learning is revisited, with space between repetitions, retention is increased and sustained over longer periods of time.

The blue line on the graph above dips into a curve to show that our memory of new facts we have learned declines over time, unless we revisit/revise that information regularly. There are 4 pink curved lines to represent how our memory retention will be higher if we revise the information we learn.

Applying to Classroom Practice

So how might we apply this in the classroom? One model from University of Waterloo suggests that we need spaced repetition, but of shorter duration over time, to retain newly learned information.

I know most math teachers will agree with this in theory. I also know many teachers find it challenging to work in this necessary review while still feeling they must march through a lesson a day to get through their curriculum and all the standards assessed on state-mandated assessments. So how can we do both?

• Warm-ups: These must be more than filler. I realize the very real issue of trying to take attendance so you can start your lesson, but warm-ups can be prime times to revisit prior learning.
• During the lesson: Whenever possible, connect the current lesson to prior learning. This creates opportunities to revisit concepts while still moving forward.
• Closure: I can not overstate the importance of closure. If you have gotten out of the habit of ‘summing it up’, use the last few minutes of class to summarize the new learning and make connections to prior learning. It is one of the best ways I have found to improve student retention and understanding.