We usually think of a test as a thermometer: it measures learning that happened somewhere else. A large body of research says tests also cause learning. Retrieving an answer from memory strengthens that memory more than seeing the answer again. This is called the testing effect, or retrieval practice.
The classic experiment
Roediger and Karpicke (2006) had students learn short prose passages under three schedules in one session: read the passage four times; read it three times and then write down everything they could recall; or read it once and recall it three times. Students then took a final recall test either five minutes or one week later.
Show data
| Condition | Recall after 5 min (%) | Recall after 1 week (%) |
|---|---|---|
| Read ×4 (SSSS) | 83 | 40 |
| Read ×3, recall ×1 (SSST) | 78 | 56 |
| Read ×1, recall ×3 (STTT) | 71 | 61 |
After five minutes, more reading meant better recall: 83 percent for four readings against 71 percent for one reading and three recalls. After a week the order reversed: 40 percent for four readings, 56 percent for three readings and one recall, and 61 percent for one reading and three recalls. The students who had spent most of their time retrieving remembered half as much again as those who had spent it rereading.
The students also predicted the opposite. Those who reread repeatedly expected to remember more. Rereading makes material feel familiar, and familiarity is easy to mistake for knowledge.
Not just for facts
A common objection is that testing only helps rote memorization. Karpicke and Blunt (2011) compared retrieval practice with building concept maps, a technique designed to promote deep, connected understanding. On a test a week later, including questions that required inference, retrieval practice produced more learning than concept mapping. It did so even when the final test asked students to draw a concept map.
Meta-analyses agree. Adesope, Trevisan and Sundararajan (2017) pooled a large body of experiments and found practice testing outperformed restudying and other comparison activities across test formats, ages and settings. Dunlosky and colleagues (2013), reviewing ten common study techniques, rated practice testing one of only two with high utility; rereading and highlighting were rated low.
Making it work
- Test before you feel ready. Retrieval that takes effort helps more than retrieval that is effortless.
- Get feedback. Checking answers corrects errors and strengthens correct answers you were unsure of.
- Space it out. Retrieval practice and spacing combine: quiz yourself again after a gap.
How Vortex applies it
Every Vortex lesson ends in a short quiz rather than a "next video" button. Answers are graded as soon as you submit, you see which answers you missed, and you can retake it until you pass, with your best grade kept. The quiz is not there to gatekeep; it is there because answering it is one of the most effective things you can do with the ten minutes after a video.
References
- 01Roediger, H. L., III, & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255.
- 02Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772–775.
- 03Adesope, O. O., Trevisan, D. A., & Sundararajan, N. (2017). Rethinking the use of tests: A meta-analysis of practice testing. Review of Educational Research, 87(3), 659–701.
- 04Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58.