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Massed and spaced study, and how to place one review so its gap fits the wait to the test.
Paper packet. Every task here also exists on screen, where it is checked automatically; answers written on paper are not assessed by Nydus. When you are back at a device, enter your answers there.
You will tell massed from spaced study, and place one review between first study and a test so the gap is about 20 to 40 percent of the wait that follows it.
You can now run a retrieve-first session and you have questions to run it with. This lesson answers the next question: when should the second session on the same material happen? Not in an hour, and not the night before. It starts with the simplest case, one review between first study and a test, because placing one review well is the skill the whole schedule in the next lesson is built from.
| Term | What it means |
|---|---|
| Massed practice | Study time all in one block, or several blocks with only minutes between them. |
| Spaced practice | The same study time split into sessions with days or weeks between them. |
| Gap | The days between first studying something and reviewing it. |
| Wait | The days between the review and the test (researchers call it the retention interval). |
| The band | A gap of about 20 to 40 percent of the wait, the rough range Cepeda and colleagues (2008) found best for tests a week or so away. |
Two hours on one night and one hour on each of two days a week apart are the same two hours. Across hundreds of experiments, the spaced arrangement is the one that held up better on a later test. Nothing extra is bought; the hours are only moved apart.
A gap works because some of the material slips. When you come back, getting it takes real retrieval, and that effort is what makes the review count. A second hour after a coffee break has no gap: nothing has slipped.
How long a gap depends on how long you need the material. The further away the test, the longer the best gap. For tests from about a week to a few weeks away, a useful check is the band: the gap before the review should be roughly 20 to 40 percent of the wait after it. A test 12 days after you first study: a review on day 3 leaves a 9-day wait, and 3 is a third of 9 — inside the band.
Another way: picture
Think of a path across a lawn. Walk it twice in a row and the grass springs back by next week. Walk it once, wait until it has half faded, and walk it again: now it stays.
Another way: steps
Cepeda and colleagues (2006) pooled 839 comparisons from 317 experiments and found spaced study ahead of massed study for keeping material over time. Their 2008 study then asked how long the gap should be. More than 1,350 people learned a set of obscure facts, reviewed them after a gap of up to three and a half months, and took a test up to a year after the review.
Two findings matter for planning. First, the best gap grew as the test got further away, but not in proportion: it was about 20 to 40 percent of a one-week wait, and only about 5 to 10 percent of a one-year wait. Second, past the best gap, scores fell off only gradually, while a gap far too short cost more. So when unsure, lean a little longer.
These are averages from groups of adults learning facts. They do not tell you your own best day, and the band is a guide for tests about one to five weeks away, not a rule for every subject.
For material you need for months — a cumulative final, a licensing exam, the foundations of a subject you will keep using — the gaps get longer and the share gets smaller. The IES practice guide (Pashler and colleagues, 2007) puts it plainly: go over key material at least twice, with the two exposures separated by several weeks to several months.
If you do not know when a test is, a review after a few days and another after a few weeks is a safe shape. What is not safe is no gap at all: everything read, reread and highlighted in the same evening.
The review is a retrieve-first session, not a reread. Start from the question list you wrote, answer before you look, and restudy only what you miss. A review that is only reading gets the timing right and throws away the effort that makes the timing matter.
A fictional college student, Dev, finishes the first unit of an introductory psychology course on day 0. The midterm is on day 35. He has time for one review of this unit before the midterm, alongside everything else.
He tries day 2: the wait would be 33 days, and 2 is about 6 percent of it — too soon, and the unit would have a month to fade. He tries day 20: the wait is 15 days, and 20 is 133 percent of it — the review has drifted toward the exam. He tries day 7: the wait is 28 days, and 7 is 25 percent of 28. Inside the band. He writes Psych unit 1 — question list, blank page on day 7 of his calendar. Because scores in the 2008 study fell off only slowly past the best gap, a day or two later would cost him little; a review on day 2 would have cost more.
"Review it tomorrow while it is fresh." Fresh is the problem: nothing has slipped, so the review asks almost nothing. A review the next day is fine as an extra; it is not where the one review should go.
"Review it the night before so it is fresh for the test." That is massed study with a delay in front of it. It helps tomorrow and is gone next month.
"A break is a gap." A walk around the block lets nothing fade. A gap is measured in days.
"There is one perfect gap." There is a band, and past it scores fall off slowly. Getting into the band matters much more than finding the exact day.
Mark the first study day and the test day.
Day 0 (Monday): first study. Day 12 (Saturday of next week): test.
The band is worked out from these two dates.
Try a review the next day.
Day 1: gap 1, wait 11 → 1 ÷ 11 ≈ 9% → too soon
Almost nothing has slipped yet, and eleven days are left to fade.
Try day 3.
Day 3: gap 3, wait 9 → 3 ÷ 9 ≈ 33% → in the band
A third of the wait sits comfortably between 20 and 40 percent.
Write the review on the calendar now.
Thursday: History unit — question list, blank page, check
A gap that is not on the calendar tends to become no gap at all.
Write plan A: both hours the night before the test.
Day 11: 7–9 pm. Gaps: 0
The second hour follows the first with nothing slipped in between.
Write plan B: one hour on day 0 and one on day 3.
Day 0: 1 hour. Day 3: 1 hour. Gap: 3 days, wait 9
Same cost, and one real gap placed in the band.
Compare what the second hour asks of you.
Plan A: continue. Plan B: find it again, then check.
Finding it again is the retrieval that spacing depends on.
Mark the dates.
Day 0: first study of the vocabulary list. Day 7: quiz.
Both dates are needed before a review day can be judged.
Try a review on day 2.
Gap 2, wait 5 → 2 ÷ 5 = 40% → in the band
Two fifths of the wait is the long end of the band.
Write it on the calendar.
A fictional student has two hours for a history unit, and the test is in two weeks. Which arrangement puts a real gap before the second hour?
A fictional plan. Luis first studies a biology unit on October 3 and decides on a 2-day gap before his one review. The test is on October 13. Complete the worked plan.
Add the gap to the first study date.
October 3 + 2 days = October a
The review date is fixed now and written on the calendar, so the gap does not depend on remembering it.
Find the wait from the review to the test.
October 13 − review date = b days
The band is judged against the wait that follows the review.
Work out the gap as a percent of that wait.
2 ÷ wait × 100 = c percent → in the band
Inside the band, so the date stays on the calendar.
A fictional student first studies a history unit on day 0; the test is on day 12. Three candidate days for the one review: day 1, day 3 and day 11. Judge each: **too soon**, **in the band** or **too late**.
| Verdict | |
|---|---|
| Review on day 1 | |
| Review on day 3 | |
| Review on day 11 |
A fictional plan. A student wants the wait from her one review to the test to be 10 days. Using the band from Cepeda and colleagues (2008) — a gap of 20 to 40 percent of that wait — how many days should separate her first study from the review?
Shortest gap: a days
Longest gap: b days
A fictional student first studies a chemistry unit on day 0, reviews it on day 4, and has the test on day 24. How many days is the wait from review to test, and what percent of that wait is the gap?
Wait from review to test: a days
Gap as a percent of the wait: b
A fictional nursing student learns the bones of the hand on day 0; the anatomy quiz is on day 26. Her one review is set for day 1. Move it until the gap is 20 to 40 percent of the wait that follows it, using as few moves as you can.
This task has no paper form; do it on a device.
Lesson test: one question per skill, one attempt each, no hints. Your answers are checked when you submit.
Two fictional plans, each with one review after first study on day 0. Plan A: a history test on day 12, review on day 2. Plan B: a chemistry exam on day 21, review on day 1. Fill in the wait, the gap as a percent of the wait, and the verdict.
| Wait (days) | Gap as percent of wait | Verdict | |
|---|---|---|---|
| Plan A (test day 12) | |||
| Plan B (exam day 21) |
You can place one review for a test a few weeks away. Pick something you are studying now, mark its test date, and put its review day on your calendar. Next: a schedule of several reviews for several topics. You can stop in the middle of any of this. Closing the page is the whole of stopping — your place and anything you had typed are already saved, and the lesson opens again where you left it.
12. Your turn: a Spanish quiz on day 7, step 3
Day 2: Spanish list — say each word before flipping
The review is a retrieval session, set for a fixed day.