Spaced repetition: design a review schedule

By Better Wise

You have already seen that effortful retrieval beats comfortable rereading, and that difficulty is only useful when it is desirable. This lesson turns that idea into a calendar: same reviews, better timing, written down before the week starts. By the end you will be able to:

• Explain the spacing effect in one sentence and give a real example
• Set expanding intervals for any card you learn
• Draft a four-week review schedule that fits your actual week
• Repair the schedule after a missed day without dumping a backlog

The spacing effect: same reviews, better timing

The _____ is the finding that an equal number of reviews produces far better long-term retention when they are spread over time than when they are massed together. Two hours of cramming on Sunday and two hours spread across a month are not the same treatment. The massed version wins on Monday's test and loses on next month's.

Why? Each time you successfully retrieve something after a partial forgetting, you re-encode it and the memory becomes easier to find again. Cramming never lets forgetting happen, so retrieval stays easy and the strengthening never occurs. Spacing is simply engineered forgetting followed by recovery.

That is the whole mechanism, so let's make it operational.

Two rules follow directly:

1. There must be a real gap. Reviews minutes apart are massed practice with extra steps. Sleep between sessions when you can.
2. The gap must not be so large that you have lost the material entirely. If a card feels completely new at review, the interval stretched too far.

Choosing expanding intervals

Start short, then grow the gap after each successful review. A workable beginner ladder:

Exact numbers matter less than the shape: short, then longer, then longer still. The ladder above is roughly _____ after each success, which is a simple rule you can apply without a spreadsheet.

Now add the decision rule for what happens at each review:

flowchart TD
    Start["Review a card"] --> Q{"Recalled it?"}
    Q -->|"Yes, easily"| Long["Stretch the gap: double it"]
    Q -->|"Yes, with effort"| Same["Keep the planned gap"]
    Q -->|"No"| Reset["Reset to 1 day and retry"]

The key insight is that _____. The calendar tells you when to sit down; the result tells you when to come back.

Note: "Easily" means you answered within a few seconds without hints. If you needed to see the first word of the answer, that counts as effortful, so keep the planned gap rather than stretching it.

Try it (project thread). Take one fact from your project topic that you learned today. Write its next four review dates using the 1, 3, 7, 16 ladder.

Show a worked answer

If you learned it on Day 0, your reviews land on Day 1, Day 4, Day 11, and Day 27. Write those dates in your calendar as four short appointments of 5 to 10 minutes, not as one long session.

Building your four-week review calendar

A schedule you never open is not a schedule. Build it around slots you already have, not around ideal study conditions.

Real example: Priya has three 20-minute slots per week, Monday, Wednesday and Friday after dinner. She has three decks: A (SQL joins), B (statistics terms), C (Spanish verbs). She fills the grid in advance:

Four weeks at that pace gives each deck roughly twelve spaced reviews, which is far more than three long weekend sessions would deliver. Notice what is missing: no decision-making during the week. The slot says what is due, and she does what is due.

Try it (project thread). Sketch your own grid for the next four weeks: three columns (or your real number of slots), four rows (weeks), and write which deck or topic fills each cell.

Guidance if you are stuck

Pick the number of slots you can honestly keep, even in a bad week. Two reliable slots beat five imaginary ones. Then assign decks so that every deck appears at least twice per week in weeks 1 and 2, and less often in weeks 3 and 4 as intervals stretch.

Missed a day? Use the catch-up rule

Missing a review is normal. The failure mode is a guilt-driven marathon that turns into a two-hour catch-up and then three weeks of avoidance.

The rule: _____. Do not slide the whole schedule forward, and do not stack days. A missed Wednesday becomes a short Thursday session of 10 to 15 minutes, and Friday runs exactly as planned.

Two more constraints keep this humane:

• Cap the catch-up. If the backlog takes more than one slot, review the cards closest to due and let the rest wait; a card seen three days late still works.
• If a card fails at review, _____, and if it fails repeatedly, mark it for rewriting rather than pushing harder.

Rules of thumb that keep the schedule alive

• Schedule reviews before new material. Retrieval first, fresh input second. It protects the reviews from being the thing you skip.
• Count reviews, not hours. Four short spaced reviews beat one long one, and they cost less total time.
• Missed a day is data, not failure. Adjust the interval or the slot size; keep the system.
• Never stack a backlog into one session. Long catch-up sessions feel productive and behave like cramming.
• Review at the same time of day. Fewer decisions means fewer skipped sessions.
• Space by sleep, not by minutes. A "review" ten minutes later is rereading.

What to carry into week one

Spacing is the cheapest upgrade available to you: same cards, same effort, better timing. Build the ladder (1, 3, 7, 16), put it in real calendar slots, let recall results adjust the gaps, and repair missed days with a short catch-up instead of a marathon. A schedule written in advance is what separates a system from good intentions.

Next, the quality of what you review matters as much as the timing, so the following lesson covers how to build flashcards that work: atomic cards, cloze deletions, and what to do with cards that keep failing.

Front: What is the spacing effect? Back: The same number of reviews produces much better long-term retention when spread over time than when massed together.

Front: Why does cramming feel effective but fail later? Back: It never lets forgetting happen, so retrieval stays easy, and easy retrieval does not strengthen memory.

Front: What shape should a beginner interval ladder have? Back: Short first, then expanding: roughly 1 day, 3 days, 7 days, 16 days.

Front: Simple rule for stretching a gap after a successful review? Back: Roughly double the previous gap.

Front: What sets the next interval for a card? Back: Your recall result at the review, not the calendar.

Front: If you recall a card easily, what do you do? Back: Stretch the gap, for example double it.

Front: If you recall a card with effort, what do you do? Back: Keep the planned gap; effortful success still counts as success.

Front: If you fail a card, what happens to its interval? Back: Reset it to the shortest step, one day, and retry.

Front: What is the catch-up rule after a missed day? Back: Do the missed reviews first, then keep the rest of the week's reviews in place.

Front: Why should you avoid stacking a backlog into one long session? Back: A long massed session behaves like cramming and gives little long-term retention.

Front: How long should a catch-up session be capped at? Back: One normal slot, around 10 to 20 minutes; review what is closest to due and let the rest wait.

Front: What order should a review slot follow? Back: Due reviews first, new material second.

Front: Minimum condition for a real spacing gap? Back: Sleep between sessions; minutes apart is massed practice.

The _____ says identical reviews spread over time beat massed reviews for long-term retention. A beginner ladder of expanding intervals looks like 1 day, _____ days, 7 days, then 16 days. After a missed day, _____. If a card fails at review, _____.