# Flashcards and spaced repetition

> Make or import flashcard decks, study them with four ratings, and see exactly how each rating decides when a card comes back.

URL: https://atheneum.app/docs/flashcards
Where in the app: Review → Flashcards, or Notebooks → open a notebook → Flashcards
Updated: 2026-10-24

Flashcard decks in Atheneum are saved with the notebook they belong to, and every card has its own schedule. When you study a card you rate how well you knew it, and that rating decides when the card comes back: soon if you struggled, later if it was easy. This is spaced repetition, the same idea Anki uses.

## Make a deck

You can make a deck in three places. All of them do the same thing: Athena writes a deck of 12 to 20 cards from the notebook and saves it.

- In the notebook: open **Flashcards** in the rail and select **Make flashcards** (or **New deck** once the notebook has decks).
- In Review: open the **Flashcards** function, pick the notebook in **Notebook**, and select **Generate flashcards**.
- In Review's rail: open **Make new**, pick the notebook and choose **Flashcards**.

The deck is named "Flashcards · " followed by the date. Cards are made from the same material as notebook summaries: each file's summary plus the notebook's notes (see [Summaries and study guides](https://atheneum.app/docs/summaries-and-study-guides)). Generating a deck uses AI credits. If Athena returns fewer than 4 usable cards, nothing is saved and the credits are returned.

You can also bring in a deck from Anki. See [Anki import and export](https://atheneum.app/docs/anki-import-export).

There is no editor for single cards: you can't add, change or delete individual cards in Atheneum. To change cards, edit them in Anki or a text file and import them as a new deck.

## See your decks

- **In the notebook**, the **Flashcards** sub-page lists the notebook's decks, newest first. Each row shows how many cards it has, how many are due ("3 due" or "all caught up") and whether it was generated or imported. The header says how many cards are due for you across the notebook. **Practice** and **Export for Anki** take you to Review.
- **In Review**, the **Flashcards** function shows each deck as a card labeled "AI-generated" or "Imported", with its card count and a due count, and buttons to study, export and delete.

## Study a deck

1. Open **Review**, select the **Flashcards** function and choose the notebook.
2. On a deck with cards due, select **Study** followed by the number due (for example **Study 12**). A deck with nothing due shows "All caught up".
3. The session opens over the whole workspace; the sidebar stays usable. Read the question, then flip the card: select it, select **Show answer**, or press Space or Enter.
4. Rate how well you knew it: **Again**, **Hard**, **Good** or **Easy**. The rating buttons appear once the card is flipped.
5. Repeat until the session ends, or select **Close** (or press Esc).

The bar at the top and "Card 4 of 12" show your place. The cards in a session are fixed when it starts, so a card you rate **Again** won't reappear in the same session. When you finish, Nyx tells you how many you reviewed and, if you marked any **Again**, that they come back in about ten minutes.

Other ways to study:

- **Review → Today**: when the selected notebook has cards due, **Up next** shows "Review N due cards" with **Start reviewing**. This studies the due cards from every deck in that notebook, up to 100 at a time.
- **After a quiz**: when **Review this next** suggests a deck, selecting it starts a session of up to 20 cards from that deck that mention what you missed. These cards are studied even if they aren't due.

### Keyboard keys

| Key | Action |
| --- | --- |
| Space or Enter | Flip the card |
| 1 | Again |
| 2 | Hard |
| 3 | Good |
| 4 | Easy |
| Esc | Close the session |

The number keys only work once the card is flipped. The keys act only when focus is in the session (or on nothing in particular), so they don't interfere with a text field or a link you've focused elsewhere.

## How it works

Each card has three numbers: an **interval** (days until it's due again), an **ease** (how fast the interval grows) and a count of **repetitions** in a row you've got right. A new card starts with interval 0, ease 2.5 and 0 repetitions, and it's due straight away.

When you rate a card:

| Rating | Next interval | Ease | Repetitions |
| --- | --- | --- | --- |
| **Again** | Due again in 10 minutes | Down by 0.2 | Back to 0 |
| **Hard** | 1 day if the card is new; otherwise the current interval × 1.2 (at least 1 day) | Down by 0.15 | Up by 1 |
| **Good** | 1 day the first time, 3 days the second time, then the current interval × ease | No change | Up by 1 |
| **Easy** | 3 days if the card is new; otherwise the current interval × the new ease × 1.3 | Up by 0.15 | Up by 1 |

Ease is kept to one decimal place (so **Hard** on a 2.5 card gives 2.4, not 2.35) and never goes below 1.3, so even a card you find hard keeps growing its interval slowly. Intervals are rounded to a tenth of a day, and the next due time is counted from the moment you rate the card, not from midnight.

An example: a new card rated **Good** every time comes back after 1 day, then 3 days, then 7.5 days (3 × 2.5), then 18.8 days. If you rate it **Again** at any point, it comes back in 10 minutes and starts again from the first step, with a slightly lower ease.

A card is **due** when its next due time has passed. Due counts on the notebook page and in Review are worked out from your own schedule.

## Shared notebooks

- Everyone in a shared notebook can study every deck in it.
- Schedules are per person. The deck's author keeps their schedule on the card; anyone else gets their own schedule, which starts the first time they rate the card. Studying someone else's deck never changes their due dates. A card you've never rated counts as due for you.
- The owner and contributors can make and import decks, using their own credits. Viewers can't.
- The owner can delete any deck; contributors can delete only decks they made.

## Delete a deck

In Review's **Flashcards** function, select the delete (trash) button on the deck. The deck and all its cards are deleted right away, without a confirmation step, for everyone in the notebook.

## Troubleshooting

- **"That rating didn't save. Try again."** The rating didn't reach the server. Rate the card again.
- **"Couldn't generate flashcards. Try again in a moment."** Athena didn't return enough usable cards. No credits were taken.
- **"Add a file or a note to this notebook first, so there's something to work from."** The notebook is empty.
- **"That's a lot in a few minutes. …"** You rated more than 300 cards in 10 minutes. Wait as long as the message says.
- **"You can study this shared notebook's decks. To add your own, ask the owner to make you a contributor."** You're a viewer.
- **A deck shows "All caught up" and no Study button.** Nothing in it is due. Come back when cards are due, or study it from **Review this next** after a quiz.

## Related

- [Anki import and export](https://atheneum.app/docs/anki-import-export)
- [Review](https://atheneum.app/docs/review)
- [Quizzes](https://atheneum.app/docs/quizzes)
- [Sharing a notebook](https://atheneum.app/docs/shared-notebooks)
- [Keyboard shortcuts and the command palette](https://atheneum.app/docs/keyboard-shortcuts)