Rereading makes material feel familiar, and familiarity is easily mistaken for knowing it. Testing yourself feels worse and works considerably better.
Reading a page for the fourth time is comfortable. The sentences arrive smoothly, nothing surprises you, and that smoothness registers as understanding. Psychologists call it fluency, and it is a poor guide to whether you could produce any of it under exam conditions.
The alternative is to close the book and try to write down what was on the page. It is uncomfortable, you will get things wrong, and it is roughly twice as effective per hour spent. Retrieving something is what strengthens your ability to retrieve it again.
The practical version: after reading a section, shut it and write the three main points from memory. Then open it and mark what you missed. What you missed is your actual revision list, and it is usually not what you would have guessed.
Spacing matters too. Two half hours on separate days beats one uninterrupted hour, because the small amount of forgetting in between is precisely what makes the second retrieval do work.
Still stuck on this one?
Reading about a topic and understanding it are different things. The Concept Clinic is one session on one topic.
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