Tests are the primary way we evaluate students. In standard instruction, a test comes at the endpoint of teaching and learning. We teach something, students try to learn it and then we test them to determine what they know.
However, testing can also be a powerful way to enhance student learning. For nearly 100 years researchers have known that when people try to recall what they learned previously, it improves their learning. This is known as the test effect or test enhanced learning.
In early laboratory studies, research subjects memorized lists of words. After this initial memorization period, some subjects were asked to recall as many words as they could (recall practice) and other subjects were given additional time to memorize the words (more study). At a later time, all of the subjects were tested. Those who had studied and then tried to recall the words out performed those who actually had spent more time studying the material.
Memorization of word lists is not the kind of learning we typically expect in college courses. But, research demonstrates that test-enhanced learning also occurs in the classroom with meaningful educational materials. This is well illustrated in a study by Jeffrey Karpicke & Janell Blunt reported in the February 2011 Journal, Science. They demonstrated that college students who read material (in this case science material) and then took a test over it, outperformed students who used other study methods. In the learning phase of the experiment students were assigned to one of four study methods:
- Study Once. Studied the material in a single study period.
- Repeated Study. Studied the material in four consecutive study periods.
- Concept Mapping. Studied the material and then created a concept map of the material.
- Retrieval Practice. Studied the material and then tried to recall as much of the material as they could remember. They studied the material again and once again tried to recall as much as they could remember.
One week after the learning phase of the experiment, students in all four groups took a short answer test that included verbatim recall and inference questions. Graphs A and B show the proportion of correct answers for each study method. Students who used retrieval practice, i.e., studied and then tried to recall what they learned, did far better than students who used the other study methods.
Why does retrieval practice work? Think of learning as involving two parts, first, as students encounter new information they try to use what they already know to make sense of it and retain it—this is called encoding. Second, learning also involves being able to recall what was previously encoded—this is recall or retrieval.
Students devote most of their study effort to encoding, trying to make sense of the material and retain it. This is important for comprehending the material and getting it into memory.
Testing, on the other hand, focuses on a different set of processes related to retrieval of what one has learned. Researchers believe that as students try to recall what they learn they reconstruct their knowledge, strengthening their ability to recall it again in the future.
In the Karpicke and Blunt research, trying to remember material had a stronger effect on what students learned than actually re-studying the material numerous times.
More research will shed light on the intricacies of the test effect. Eventually we will better understand when and why testing can boost student learning. But the there are important classroom applications that we can use now. Here are a few suggestions.
Use retrieval practice as a learning strategy in your class. Think of where you can use tests in your class as a tool to help students learn the material and not simply to evaluate what they learned. A short written response in the middle or at the end of a class period may help students consolidate the class concepts. Or, practice tests could be used in class to help students prepare for a later graded test.
Encourage students to test themselves. Encourage students to do more self-testing when they study. This may be a hard sell; research indicates that students don’t believe that testing is an effective way to learn. In the Karpicke and Blunt experiments, students thought that retrieval practice would be the least effective of the four study methods. Moreover, self testing can be tedious.
Suggest ways that students can break up their reading assignments into segments. Propose that they read a segment then put the material aside and try to remember as much as they can. Not only will the act of retrieval practice improve their learning, but they will be able to identify gaps in their understanding. They can then re-study the material more strategically, concentrating on what they don’t yet know very well.
Karpicke, J. & Blunt, R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science. 331, 772-775.
Roediger, H., McDaniel, M., & McDermott, K. (March, 2006). Test enhanced learning. APS Observer. Vol. 19, No. 3.