Generation effect
The generation effect is the way you remember something better when you come up with the answer yourself instead of just reading it. The act of producing it from your own head makes the memory stick harder than passively taking it in.
The idea is simple. If you read "Paris is the capital of France," it goes in and out. If you cover the answer and force yourself to say "Paris," your brain has to dig for it, and that digging is what builds the memory. You remember things you made more than things you were handed.
It works even when your first try is wrong. Guessing "Lyon," finding out it's Paris, then trying again still beats reading the right answer straight away. The struggle is the point. Researchers have shown this across hundreds of studies, in different ages and languages, and it's one of the steadiest findings in memory science.
This is why highlighting and rereading feel productive but do little. They are passive. The fix is to make yourself produce the answer: cover the page, ask yourself the question, write it from memory, then check.
Lena has a list of 40 anatomy terms. Instead of rereading them, she covers the definition and tries to say each one out loud first. She gets about half wrong on the first pass, but checking each one right after means the names stick by the second round.