Why students forget what they study—and how to remember more

Humans forget things. Sometimes surprisingly, high school students are humans too.

You may have seen a dramatic statistic claiming that students forget 95% of what they learn after three days. It sounds scientific, it makes a fantastic headline—and it is not a reliable description of human memory.

The good news is that the useful idea underneath it still holds: if you learn something once and never try to retrieve it again, it becomes harder to recall. Spacing your study and actively pulling information from memory can make learning much more durable.

What the forgetting curve actually tells us

Hermann Ebbinghaus carried out early memory experiments on himself in the nineteenth century. He learned lists of nonsense syllables, then measured how much faster he could relearn them after different delays. His work helped describe a forgetting curve: forgetting can be rapid after initial learning and then slow down over time.

But Ebbinghaus was not measuring how much every teenager remembers from every school lesson. He used one participant—himself—learning artificial material under controlled conditions. His “savings” measure also described time saved when relearning, not a simple percentage of facts still sitting intact in the brain.

So there is no defensible rule that every student remembers exactly one-third after one day, 5% after three days, or permanently retains 95% after five repetitions. Memory varies with the person, material, prior knowledge, sleep, attention, study method and how long the learning needs to last.

The practical lesson: retrieve, space and check

Research does consistently support two useful study ideas:

1. Retrieval practice

Try to produce the answer from memory instead of merely looking at it again. That might mean answering a practice question, explaining the idea aloud, drawing a diagram from memory or using a flashcard properly.

The “properly” matters. Reading the front of a card, immediately flipping it over and thinking “yep, that looks familiar” is not retrieval practice. Pause, commit to an answer, then check it.

2. Spaced practice

Return to the material across multiple study sessions rather than cramming the same total time into one evening. Some forgetting between sessions is useful: the effort involved in retrieving the answer helps strengthen later recall.

There is no single perfect schedule for every topic. A useful starting pattern might be:

• a quick retrieval attempt later the same day or the next day;
• another attempt a few days later;
• another the following week; and
• longer gaps once recall becomes reliable.

If you cannot retrieve the idea, shorten the next gap and rebuild your understanding. If recall is easy several times in a row, lengthen the gap. The schedule should respond to performance rather than obey an attractive diagram on the internet.

Feedback is part of the process

Practising the wrong answer very confidently is not the goal. Check answers against notes, worked solutions, marking schedules or teacher feedback. Then correct the misunderstanding and try the question again later without the solution open.

This is especially important for subjects where method matters. In Maths or Physics, a final number can be right for the wrong reason. In English, remembering a quotation is only useful if you can analyse it and connect it to the question.

A simple study loop

1. Understand: learn the idea well enough that it makes sense.
2. Close the notes: remove the answer from view.
3. Retrieve: answer a question or explain the idea from memory.
4. Check: compare your response with a trustworthy source.
5. Correct: fix errors and identify what confused you.
6. Return later: try again after a sensible delay.

That loop is less comforting than highlighting a page because it reveals what you do not know. That is precisely why it is useful.

What parents can do

You do not need to become the household Chemistry expert. Ask your child to teach you one idea without their notes. Prompt them with questions, let them pause, and encourage them to check anything they were unsure about.

You can also help them plan several short returns to a topic instead of one heroic late-night cram. Keep the emphasis on identifying gaps rather than judging every wrong answer. A mistake found during study is much cheaper than the same mistake found in the exam.

What students should remember

There is no magic “five repetitions” switch that locks knowledge away forever. Learning lasts when you understand it, retrieve it, correct it and revisit it over time. Different topics will need different amounts of practice.

If you want to read further, see this review of retrieval-practice research and this review of distributed practice.

Article by Jimmy Li

Was this article helpful? Let me know at team@mytuition.nz.