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Study skills

Read it once, keep it: the margin-summary method

A simple note-taking habit that forces you to think while you read, so the ideas are still there when you need them.

Based on a video lecture by a philosophy professor at UNC Greensboro · 8 min read

The whole method in one picture: every paragraph gets a short summary, written in your own words, in the margin.

In this post

1. The core principle
2. The problem: reading on autopilot
3. The method: cumulative margin summaries
4. "But it takes too long"
5. Does it actually work?

1The core principle

If you want to remember what you read, you have to engage with what it means. Seeing the words isn't enough. The professor calls this the text's semantic content, which is just a fancy phrase for its meaning.

You could try to do this by concentrating really hard. That sometimes works. A better plan is to follow a procedure that forces you to think through the ideas every time, whether you feel focused or not.

The procedure in this post is a specific kind of marginalia, which just means notes written in the margins of a page. It isn't "take some notes." It's a precise routine, and the details are what make it work.

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2The problem: reading on autopilot

If you drive, you've probably arrived somewhere and realized you don't remember the last ten minutes. You turned left, stopped at a stop sign, turned right, and got there. Driving had become muscle memory, so your mind was somewhere else the whole time.

That's exactly what you don't want when you read. Yet it's how most students read most things. Their eyes pass over the words, the pages go by, and at the end almost nothing has stuck.

Same page, same time spent looking at it. Only one of these readers will remember it next week.

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3The method: cumulative margin summaries

Here's the routine, step by step.

1. Paragraph 1: read it, then write a one-sentence summary in the margin.
2. Paragraph 2: read it, then write a one-sentence summary of it.
3. Paragraph 3: now write two sentences. The first sums up paragraphs 1 and 2 together. The second sums up paragraph 3.
4. Paragraph 4 and on: keep going the same way. One sentence for everything so far, one sentence for the new paragraph.

The highlighted line is the key move. From paragraph 3 on, you squeeze everything you've read so far into a single sentence.

Why it works

• You can copy without understanding, but you can't summarize without it. If a paragraph has six sentences, writing six sentences in the margin proves nothing. Boiling them down to one means you have to find the central idea they share.
• The "everything so far" sentence makes you connect ideas. You can't fit several paragraphs into one sentence, so you have to decide what matters most and how the pieces fit together. That decision is where the learning happens.
• You end up with a built-in review sheet. To refresh your memory later, you read one sentence per paragraph instead of the whole text.

Summary, not copying. If you could write it without thinking, it doesn't count.

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4"But it takes too long"

This is the first objection everyone raises. The answer is that the real waste of time is reading something and keeping none of it. If you're going to read that way, you might as well go sailing or play video games instead.

The professor sketches a rough semester with 20 assigned readings to show the difference:

Hours are the professor's illustration, drawn to scale. Passive reading gets you to about a D+ before cramming; margin summaries get you to about an A− before a short review.

Slightly less total time, and a much better result. He's open about the numbers being made up, so adjust them however you like. Even if margin summaries took four hours per reading instead of three, you'd spend a little more time overall and still come out far ahead.

There are extra benefits the chart doesn't show:

• You walk into lectures already understanding the material, so you get more out of them.
• There's no end-of-semester panic, which means much less stress.
• You get faster with practice. It never becomes as quick as skimming, but it gets to a good pace.

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5Does it actually work?

The professor calls this method his superpower. He went to Williams College and graduated in the top 2% of his class, then studied at Oxford and Cambridge and earned a PhD from Berkeley. He describes himself as "medium level smart." The difference, he says, is that he showed up to everything having already thought through the material.

He started taking margin notes in high school in 2002, after a teacher suggested it. He refined it into the exact summary routine above early in college.

The economics story

In 2006 he took an intro economics course. On the first day, the professor asked the room, "What is economics?" There was a long silence. He raised his hand and answered: the study of the allocation of scarce resources. The professor said "correct" and moved on.

After class, a classmate asked how he knew. It was the first definition in the assigned chapter. She had read it too, but it hadn't stuck.

The difference was what he did after reading that line. He wrote it down, rephrased it in his own words, and stopped to think about it with examples:

His thought process in the margin. Money is scarce. So is sand, which people need for glass. Studying who gets the sand and what they pay for it is economics.

That one minute of thinking is why the definition stuck. He tells this story fifteen years later, off the cuff, without looking it up, and still gets the definition right.

When you have to think through what something means, you remember it.

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Adapted from a video lecture on how to remember what you read. Sections 1 to 5 of the talk.