Why Highlighting Your Notes Is Wasting Your Time
I once highlighted an entire textbook and still failed the test. Here is why highlighting feels productive, why it rarely works, and what to do instead.
5 min read
In my second year I bought a set of four highlighters — yellow, green, pink, orange — for about ₦1,200, and I felt like a serious student. I had a system: yellow for definitions, green for examples, pink for anything the lecturer repeated twice, orange for "very important". My notes looked like a decorated aso-ebi. My friends borrowed them because they looked organised.
Then the test came. Twenty marks. I scored nine.
That evening I flipped through my beautiful pages and realised something uncomfortable: I could recognise every highlighted line, but I could not produce a single one from memory. Recognition and recall are not the same thing, and exams only pay for recall.
Why highlighting feels so good
Highlighting is satisfying because it gives you three false signals at once:
- Progress. Colour spreads across the page, so it looks like work is happening.
- Understanding. Choosing what to highlight feels like judgement, but usually you are just marking whatever sounds important-ish.
- Safety. You tell yourself, "I will come back to the highlighted parts." Most students never do, and if they do, they only reread.
The real problem is that highlighting is a passive activity. Your hand moves; your memory does not. Rereading highlighted text later makes the words feel familiar, and familiarity tricks you into thinking you know the material. In the hall, with a blank sheet in front of you, familiarity gives you nothing.
The three ways highlighting quietly hurts you
1. It hides the structure of a topic
A topic is not a list of important sentences. It is a structure: cause and effect, steps in order, categories with differences. When you highlight, you break the topic into disconnected glowing lines and lose the shape. That is why students can quote a definition of osmosis and still fail a question that asks them to explain why a cell swells.
2. It postpones thinking
Highlighting says, "This matters, I will deal with it later." Multiply that by 200 pages and you have postponed all the thinking to the week before the exam, which is exactly when you have no time for thinking.
3. It over-marks
Be honest: by chapter three, you are highlighting more than half the page. If everything is important, nothing is marked.
What to do instead: five methods that actually pay
You do not have to abandon your pens. You have to replace the passive part with something that forces your brain to produce information.
Method 1: Margin questions
Instead of highlighting a paragraph, write a question in the margin that the paragraph answers.
- Paragraph about inflation causes → margin: "Three causes of inflation?"
- Paragraph about photosynthesis stages → margin: "What happens in the light-dependent stage?"
Now your textbook has become a question bank. Later you cover the page and answer your own margins. That is testing, not decoration.
Method 2: The one-sentence summary
At the end of every section, write one sentence in your own words, no copying. If you cannot write it, you did not understand it — go back now, not in December.
I keep these summaries on a single page per topic. Before an exam, that page is worth more than the whole chapter.
Method 3: Blank page recall
Read a section, close the book, then write everything you remember on a blank sheet. Open the book and correct yourself in a different pen. The gaps you find are your real study list.
The first time I did this with a Physics topic, I discovered I could not remember three of the five conditions I had "known" for two weeks.
Method 4: Convert to a table or diagram
If the material compares things, force it into a table. Comparison questions are lecturer favourites.
| Passive study | Active study |
|---|---|
| Highlighting | Writing margin questions |
| Rereading notes | Blank page recall |
| Copying lecturer's slides | Rewriting them in your own words |
| Watching a solved example | Solving it yourself, book closed |
Method 5: Teach it out loud
Explain the topic to a roommate, a sibling, or an empty chair. The moment you start saying "so, basically... eh..." you have found the weak point. This is the Feynman idea and it costs nothing but honesty.
If you still want to use a highlighter, use it properly
There is a narrow, useful role for highlighting:
- Only after you have read a section once. Never on the first pass.
- Maximum three lines per page. Force yourself to choose.
- One colour. Colour systems are admin work in disguise.
- Highlight things that are hard to reconstruct — a specific figure, a date, an exact legal phrase, a formula constant — not general explanations you can rebuild with understanding.
Used that way, the highlighter becomes a pointer to the two or three items on the page that genuinely need raw memory.
A simple weekly rhythm
Here is the routine I used from third year, and my results changed:
- Lecture day: rewrite the lecture into your own words within 24 hours, in short numbered points.
- Same evening: add margin questions to those points.
- Every weekend: blank page recall for the week's topics, 30 minutes per course.
- Every month: answer past questions on those topics under time pressure, no book.
Notice that highlighting appears nowhere, and that all four steps require you to produce something. That is the whole secret. Study is not what you put into your eyes; it is what you can pull out of your head under pressure.
What changed for me
The semester I stopped highlighting and started writing margin questions, two things happened. First, my reading got slower — genuinely slower, maybe 30 percent fewer pages per hour. Second, my scores went up, especially in theory questions where I used to write vague answers.
Slower reading, better marks. That trade is worth making every single time.
So look at your notebook now. If your last chapter is glowing yellow but you cannot explain it to someone in two minutes, what would happen if you closed the book and tried to write it from memory instead?
