Why Re-reading and Highlighting Don't Work (and What to Do Instead)

The two most popular study habits are also two of the least effective. Here's why re-reading and highlighting fail, and what to replace them with.

Walk into any library during exam season and you'll see the same two activities everywhere: students re-reading their notes and students highlighting textbooks in three colours. Both feel like studying. Both are, unfortunately, among the least effective things you can do with your time.

The illusion of competence

When you re-read a page, it gets easier to read each time. Your brain interprets that fluency as understanding, 'I know this, it feels familiar.' Researchers call this the illusion of competence. The problem is that recognising information when it's in front of you is a completely different skill from producing it when it isn't. Exams test the second skill; re-reading only trains the first.

Why highlighting falls short

Highlighting feels active because your hand is moving, but it's a passive task in disguise. It mostly involves deciding what looks important, not engaging with what the material means. Worse, students tend to highlight far too much, turning whole pages yellow and flattening the difference between key ideas and supporting detail. The act of marking text rarely transfers anything into long-term memory.

What to do instead

• Self-test. After reading a section, close the book and write down or say aloud the main points from memory.
• Summarise in your own words. Rephrasing forces genuine understanding in a way copying or highlighting never will.
• Ask 'why' and 'how' questions. Don't just learn that something is true, make yourself explain the mechanism behind it.
• Space your reviews. Come back to the material days later and test yourself again.

A better way to read

You don't have to abandon reading altogether, you just have to follow it with retrieval. Read a section once with full attention, then immediately turn it into questions and answer them without looking. If you can't, you've found exactly what to study next. That single change, from passive review to active testing, is the difference between feeling prepared and being prepared.