Long-term memory
Long-term memory is the part of your mind that holds knowledge for days, months, or years. Things land there when you come back to them again and again over time, not when you read them once. It's where stuff you actually know lives.
Your brain has a short store and a long store. The short one fades fast. A name, a formula, a date you read once is gone by the next day. Long-term memory is the deep store, and it's the one you want for an exam. The catch is that getting things in there is slow.
One pass doesn't do it. You have to meet the same idea more than once, spread out across days. Each time you pull it back up, it gets a little more solid. That's why a single long study night feels productive but disappears by the weekend. Spacing the same material over time is what makes it stick.
So the goal isn't to read more. It's to keep coming back, in small doses, until the idea moves from "I just saw this" to "I know this."
Mara reads her biology chapter once and feels ready. Two days later she can't remember half of it. She switches to short reviews: a bit the next day, again after three days, again a week on. By the exam the same facts come up without effort.