Search for "forgetting curve" or "spaced repetition" and you get a long list of apps. All of them say they remind you to review at scientifically timed intervals, but under the hood they split into two kinds, and which kind fits you depends on what you are trying to remember. Get that wrong and it won't stick, no matter how good the app is.

This article is written by the official site of Ebbing, a review scheduling app based on the forgetting curve. With that stated, it lays out the choice as neutrally as it can.

Two kinds: flashcard type and schedule type

Flashcard type (reviews one card at a time)

This is the Anki and Quizlet model. You make cards with a question on the front and an answer on the back, and each card gets its own next review date.

  • Good for: vocabulary, medical terms, dates, statute numbers, anything that breaks down into one question, one answer
  • Strength: intervals are optimized per card, so words you know fade out of rotation and only the hard ones keep coming back
  • Weakness: making cards takes real effort. Material you work through by chapter, like a problem book or a textbook, is hard to turn into cards

Schedule type (sets review days per material or section)

In this model you register what you studied as is, like "chapter 3 of the problem book" or "pages 20 to 35 of the textbook," and the app places review days for that section along the forgetting curve. Ebbing is this kind.

  • Good for: certification problem books, textbooks, lecture notes, recorded lectures, any study where the material already exists
  • Strength: input is just "what I did today," with no cards to make. Several materials can run in parallel with a single list of today's reviews
  • Weakness: no per-word optimization. If vocabulary is all you want to master, the flashcard type is finer-grained

Knowledge that breaks into cards: flashcard type. Study that moves through material chapter by chapter: schedule type.

Both rest on the same principle: recall at expanding intervals just as you start to forget (the science of spaced repetition). The only difference is the unit, a single card or a section of material.

Five criteria for choosing

1. Does what you are learning break into one question, one answer?

Check this first. Vocabulary and term memorization point to the flashcard type; solving problem books and understanding textbooks point to the schedule type. If you have both (a certification with terms to memorize and past papers to work through, say), using both is fine.

2. Can you keep up the input?

The biggest reason review apps get abandoned is that entering things becomes a chore. The flashcard type takes time to make cards: 20 words a day means 10 to 15 minutes of card-making on top of study time. The schedule type only needs a one-line entry for today's section, but in exchange you decide what the review consists of.

The question is not which is better, but which amount of input can you sustain for three months.

3. Does "today's work" appear on a single screen?

When you have several materials or subjects, whether the app shows "which material, which section, today" as one list is decisive. Without that, you end up managing it in your head, and it breaks down as soon as the item count grows (Managing reviews when you have hundreds of items).

4. Do notifications tell you there is a review today?

Reviews work because they happen just as you start to forget. Miss the day, and a week later it is close to relearning. Check that the app notifies you that today has reviews due, and that you can set the time to one you will not ignore.

5. Can you change the review intervals?

A default pattern (say 1 day, 3 days, 1 week, 2 weeks, 1 month) is designed to fit most studying. But when an exam is near, tightening the intervals makes more sense (Planning reviews backward from your exam date). See whether you can adjust the intervals to your goal.

Isn't a paper planner or a spreadsheet enough?

It can be. While the number of items is small, writing "review this section on the 12th" in a planner works fine.

It breaks down somewhere past 30 items. Each section you learn today generates five review dates, so within two weeks you are managing 50 to 70 entries by hand. When "a review was due and I didn't notice" or "I can't tell how far I've reviewed" starts happening, that is the signal to move to an app.

Where Ebbing fits

As the official site, here is an honest account of who Ebbing suits and who it does not.

  • A good fit: people preparing for certifications, entrance exams, or professional study who work through problem books and textbooks chapter by chapter. People running several materials at once. People who would rather spend card-making time on studying
  • Not a good fit: people who want to cycle vocabulary word by word (the flashcard type suits that better). Android users (Ebbing is iOS only)

Register a section you studied, and review days are placed automatically on the forgetting curve (1, 3, 7, 14, and 30 days later), with only today's reviews shown on the home screen. It is free to start, so try it with a single problem book.

Summary

  • Review apps split into the flashcard type (per card) and the schedule type (per material or section)
  • Knowledge that breaks into Q&A: flashcard type. Working through material: schedule type. Using both is fine
  • Choose by whether you can sustain the input, whether today's work is one list, notifications, and adjustable intervals
  • Planners and spreadsheets break down around 30 items. That is the signal to move to an app
  • Ebbing suits working through problem books and textbooks by section. For word-by-word memorization, use a flashcard app