How to study for an exam in 3 days (without studying everything)

You can study for an exam in 3 days, but you can't study everything. That's the first decision, and the one almost nobody makes: with three days left, the person who tries to get through every slide shows up having seen a lot and knowing little. With three days, choosing what not to study is part of studying.

The plan that works has three parts: a first day to decide what's on the exam and understand the heaviest topics, a second to finish understanding and start practicing, and a third to practice like it's the real thing, go over what you missed, and sleep. No rereading from lecture one.

Here's how I do it as a final-year computer engineering student, with a real case: a Databases midterm with six topics (ER modeling, the relational model, SQL, normalization, transactions and indexes) that landed in the same week as a project deadline for another course.

Before you start: decide what's in and what's out

The first hour of day one isn't for studying. It's for deciding. It's the most valuable hour of the three days.

1. Get everything in one place. The slides, your notes, the problem sets and past papers if there are any. If something's missing, ask for it now: there's no time to wait for a reply on the last day.
2. List the topics and give each one two marks: how much it's worth on the exam and how well you know it today.
3. Look at a past paper, even if you can't solve it yet. In ten minutes it tells you what kind of questions your professor asks and which topics always show up.
4. Sort the topics into three groups: high weight and you don't know it (first), high weight and you sort of know it (second), and low weight (a quick pass if there's time left, or never).

In Databases, past papers always had one SQL query and one normalization problem, and rarely more than one short question on indexes. That alone organized my three days: SQL and normalization first, indexes last and lightly.

If there are no past papers, ask. A classmate who already took the course, the course forum, a TA. Knowing what the professor asks is worth more than any single hour of studying.

Day 1: understand the heavy stuff

With the list sorted, the rest of the first day goes to the topics in the first group. Not to read them: to understand them.

• Skim the whole slide deck quickly, so you know what it covers and where the hard slides are.
• Go back to the hard ones, slowly. If a slide says "Boyce-Codd normal form" next to a diagram with arrows, the real question is what problem it solves and how you'd spot a table that breaks it. A three-word slide is almost never everything you need to know: it's what the professor used to remember what to say.
• After each topic, close everything and explain it out loud in two or three minutes. Wherever you get stuck is where you go back.
• Do one problem from each topic the same day, even if you get it wrong. A problem you botch today tells you what to study tomorrow.

What not to do: rewrite the slides neatly, make color-coded summaries or highlight. In three days there's no time for things that only feel productive.

Day 2: finish understanding and start practicing

The morning of day two goes to the second group of topics, with the same routine but shorter: you already sort of know them, so it's about filling gaps, not starting from zero.

The afternoon switches modes. You stop looking at the material and start pulling it out of memory:

• Work problems with topics mixed together, not one topic at a time. On the exam, nobody tells you which topic a question is from.
• Finish the problem before you look at the solution. Even if it's wrong. Reading a worked solution and thinking "yeah, I get it" is recognizing, not knowing how to do it.
• Write down what you got wrong on a separate sheet. That sheet is the only thing you'll study on day three.

Before bed, ten minutes on what you covered on day one, without looking: what do you remember about each topic? Coming back to something the next day, instead of saving it for the end, is what makes it stick. It's the same idea as spaced repetition, squeezed into three days.

Day 3: practice like it's the real exam

The last day has three parts.

The morning is a mock exam. If there's a past paper, do the whole thing on a timer, no notes, in the real exam time. If there isn't, build one from mixed problem-set questions. Then grade it honestly and add whatever went wrong to your mistakes sheet.

The afternoon is for the mistakes sheet. Only that. Go back to each thing you missed, understand it, and try it again without looking. If there's time left, then yes: a quick pass through the third-group topics, looking for the bare minimum to answer a short question.

The night ends early. Pack your bag, eat dinner and sleep. What you studied over these three days settles in while you sleep, and showing up without sleep wipes out exactly what you knew. I went into more detail in what to do the night before an exam.

How to make every hour count

Three days go by fast, and they're almost always lost in the breaks, not the studying.

• 50-minute blocks with 10-minute breaks. The break needs an end: a timer, not "a bit".
• Your phone in another room during the blocks.
• Start each day with the hardest thing, while your head is fresh, and leave the mechanical stuff for the afternoon.
• Don't stay stuck for more than fifteen minutes. If a slide or a problem doesn't click, mark it and move on. Sometimes it makes sense once you see the next topic, and if not, you ask.

That last one is what used to eat most of my time. When you're short on time, an unanswered question can swallow a whole afternoon. That's what I use Ask for in Filmina, the web app I built for studying from lecture slides: it's a chat with the whole lecture, you ask what doesn't make sense and it answers from your slides, telling you which ones the answer comes from so you can go look. It's explained in asking about the lecture. Without an app, the fallback is the same idea: write your questions down and send them to a classmate or your professor in one go, instead of wrestling with each one alone.

If you have more than one exam in those days

It happens more than you'd think. If you have two exams in the same three days, don't study both halfway in parallel: give each day one main exam and a short slot for the other. The one that comes first gets more hours, but the second never drops to zero, because coming back to it every day is what keeps it from fading.

And if you have a week instead of three days, the plan stretches out more calmly: I laid it out day by day in how to study for an exam in a week.

Frequently asked questions

Can you pass an exam by studying for 3 days?

Yes, in most courses, if you choose well what to study. Three days is enough to understand and practice the topics that matter most, not to cover all the material in the same depth.

How many hours a day should you study with 3 days left?

It depends on the course and how much you already know, but five to seven hours of real studying a day is a reasonable range. More hours don't help if they're spent rereading, and cutting sleep to gain time ends up costing more than it gives.

What should I study first if I'm short on time?

The topics that carry the most weight on the exam and that you know least. To find out which ones carry the most weight, look at past papers or ask someone who already took the course.

Should I pull an all-nighter before the exam?

No. Skipping a night's sleep makes you remember worse exactly what you studied. It's better to stop at a reasonable hour, go over only what you got wrong, and sleep.