How Tests Lead to Learning

by Site Author

What do students look like when they study? The image I have is of an undergraduate, hunched over her textbook. She reads through the textbook and her notes. Maybe she puts together a little outline, summarizing all of the material.

That type of study is called “encoding.” She gathers the material from class together, organizes it, and examines it. It’s as though she fills a notebook with the knowledge, and then place the notebook on the metaphorical bookshelf in her mind. When it’s time for the exam, the student retrieves the notebook from the shelf, and uses it to answer the questions on the exam.

There’s now good evidence—definitive evidence—that both writing in the notebook and taking the notebook off the shelf lead to learning. Just recalling things you’ve learned for an exam, without the help of notes, improves your ability to remember those things later. Psychologists sometimes call this the “testing effect:” taking tests actually improves learning. As Jeffrey Karpicke, an expert in the area, puts it “tests not only assess learning, but also produce it.”

The bar chart, below, comes from some of Karpicke’s work. In one study, Karpicke asked 120 students to read two passages from a science textbook. For the first passage, the students were asked to create a concept map. For the second passage, students studied the passage and then took a “free-recall test.” Though creating a concept map did help, the free-recall test was more effective.


This idea is not new. Consider, for instance, this passage from an 1890—1890!—psychology textbook:

A curious peculiarity of our memory is that things are impressed better by active than by passive repetition. I mean that in learning (by heart, for example), when we almost know the piece, it pays better to wait and recollect by an effort from within, than to look at the book again.

All of this is to say that effective learning happens when people mix both encoding and retrieval. You have to absorb and then you have to test. Both matter.