Flashcard Review ①: Scientific Review with the FSRS Anti-Forgetting Algorithm¶

💡📖 Flashcard Series Navigation This series helps you master flashcard creation and scientific review in MN4.

Creating flashcards:

For beginners: ① Understanding flashcards and review card decks ② Adding cards to a review card deck

Advanced: ③ Setting the flashcard front and back

Scientific review:

For beginners: ① Scientific review with the FSRS anti-forgetting algorithm (this page)

Advanced: ② Tracing the source context

💡On This Page

You've already created your flashcards; now it's time to start your scientific review. This page will teach you:

How to use full-screen review mode

How to choose review intervals based on how well you remember

How to filter and sort the cards you need to review

⚠️Prerequisites: First read parts ① and ② of the flashcard creation series, and make sure you already have cards added to a review card deck.

1 The FSRS Algorithm and MarginNote 4 Review Features¶

What Is the FSRS Algorithm?¶

FSRS (Free Spaced Repetition Scheduler) is a scientific spaced-repetition algorithm that automatically calculates your next review time based on your memory feedback, helping you review just before you forget and study more efficiently. MarginNote 4 uses this algorithm so you never have to schedule reviews manually—the system intelligently arranges the best moment for each review.

MN4's Review Advantages¶

Unlike MN3, which required switching between study mode and review mode, MN4 enables seamless flow between the document, mind map, and review card deck: while reviewing, you can see a card's position in the mind map and its context in the document at any time, and edit notes and review cards without switching between functional areas.

2 Starting a Review¶

2.1 Entering Full-Screen Review Mode¶

In a review card deck, tap the ▶ at the top of the view to enter the Anki-style, full-screen card review mode.

2.2 Quick Review Workflow (For Beginners)¶

Reviewing for the first time? Follow these steps:

When you see the front of the card (the question), try to recall the answer
Tap the screen or tap Flip to see the back of the card (the answer)
Based on how well you remembered, choose: Again, Hard, Good, Easy
The app automatically advances to the next card

✅ Repeat these steps to review all due cards

💡Tips for Your First Time:

When unsure, choose "Hard" or "Good"

After reviewing 10-20 cards, you'll gradually get into the rhythm

Later you can try advanced features like filtering, sorting, and Speech

3 Review Actions in Detail¶

3.1 Rating Your Recall and Choosing the Next Review Time¶

During review, use the front of the flashcard to recall the back or the clozed content on your own. After flipping, you can view the card's original text and choose the spaced-review interval based on how well you remembered.

The four recall-rating options:

Again 5m: the next review is due in 5 minutes; best for flashcards you have almost no memory of
Hard 10m: the next review is due in 10 minutes; best for flashcards you remember poorly
Good 1d: the next review is due in 1 day; best for flashcards you remember fairly well
Easy 2d: the next review is due in 2 days; best for flashcards you've already memorized solidly

💡How Does FSRS Work?

The system automatically calculates the best review time based on your choices. The more often you choose "Hard," the shorter the interval becomes; the more often you choose "Easy," the longer the interval becomes. This way, you neither waste time over-reviewing nor wait until you've forgotten to review.

⚠️ Tip: Honestly report how well you remember. Don't choose "Easy" just to cut down on reviews—it will weaken your retention.

Turning On Review Reminders:

If you've enabled Review Reminder, you'll get an in-app pop-up notification when a card is due for review (See how to turn on Review Reminders)

3.2 Favoriting (Adding a Star)¶

Tap the ★ icon in the top-left corner of a card to favorite it. In later reviews, you can filter for favorited cards to do focused review.

💡When to Use This:

Mark key cards for focused review before an exam

Mark hard-to-remember cards to reinforce them repeatedly

Mark error-prone cards to give them extra attention

3.3 Annotation¶

Annotation

Tap the annotation button in the top-right corner of a card (shown by the icon above) to annotate. This is handy for review tasks such as writing out classical poems or vocabulary from memory, jotting down mnemonics, recalling and organizing key points, and working through calculations.

Annotation features:

Provides 2 annotation modes: 🖼️ Image, 🖼️ Image;
You can annotate by handwriting or typing.
Annotations are not saved in the card; they're only visible in the review annotation mode.

💡Why Aren't Annotations Saved in the Card?

Annotations are your temporary thoughts and scratch work during review, so they don't clutter the original card content. Each time you review, you can annotate again to test whether you've truly mastered the material.

3.4 Speech¶

Speech

Tap Speech in the top-right corner (shown by the icon above) to enter Speech review mode; a speech control bar appears at the bottom of the screen.

Speech features:

The system automatically reads aloud the text on the card front and the OCR text layer of images;
After finishing the front, it automatically flips to the back and continues reading the back;
Tap **⏪, ⏩** to switch to the previous or next card and read it aloud automatically.

💡Benefits of Combining Speech with Review

According to memory theory, multisensory stimulation significantly improves retention:

Dual-channel memory (auditory + visual): improves retention by 30-50% compared with reading alone

Hands-free: ideal for bite-sized review while commuting, exercising, and so on

Stronger language learning: especially effective for foreign-language vocabulary, classical poems, and similar content

Less eye strain: during long review sessions, auditory input can relieve eye fatigue

💡Suggested use: For your first pass, rely mainly on vision; for your second, consolidating pass, you can use Speech mode for auditory review while commuting or before bed.

Changing Speech Settings:

MarginNote 4 can read text aloud, and you can adjust the speech speed and language.

Speech speed: choose from Default, Slow, Fast, or Very Fast
Speech language: supports Automatic, English, Mandarin, Portuguese, French, German, Italian, Spanish, Russian, Japanese, and Korean

3.5 Flip¶

Tap Flip in the top-right corner to force the current card to flip once.

💡What the Flip Button Is For

Although tapping the screen also flips a card, the Flip button is more convenient in these situations:

In Speech mode: during automatic reading, tapping the screen may trigger other actions, so the Flip button is more precise

In annotation mode: while annotating, a tap on the screen may be interpreted as an annotation stroke, so the Flip button avoids mistaken actions

3.6 Switching to the Previous/Next Card¶

How to do it:

Swipe left or right with your finger
If Speech mode is on, you can switch from the speech control bar

4 Personalizing Your Review¶

In review mode, you can decide which cards to review and in what order.

💡Benefits of Personalized Review

Targeted review: concentrating on your weak spots is 2-3 times more efficient than spreading time evenly

Flexible ordering: reviewing in textbook order helps you build a knowledge framework, while random order helps you avoid memorizing by position

Organized by category: reviewing by tag, color, or document matches how the brain remembers in categories

Lower cognitive load: reviewing only one type of card at a time reduces the cost of cognitive switching

4.1 Filtering Cards to Review a Subset¶

Tap the funnel icon at the top of the review view to filter cards by whether they're due, their recall rating, whether they're favorited, the tags they contain, their source document, color, and more—so you can do more targeted, focused review.

Filter options:

Due: filter for cards that are already due
Rating: filter by rating—Hard, Medium, Easy
Favorites: filter for favorited cards
Tags: filter for cards that contain certain tags
Document: filter for cards from a specific source document
Color: filter for cards of a specific color

Combining multiple filters:

You can select multiple filter conditions at once; they're combined as an intersection. For example:

Filter "Due + tag #Key + rating Hard" → find the key, difficult cards that most need review
Filter "Document is Advanced Mathematics + Color is red" → review the red-marked cards in Advanced Mathematics
Filter "Favorites + Due" → prioritize the important cards you've favorited

💡Common Filtering Scenarios:

Daily review: filter only "Due" to review just the cards that need reviewing

Pre-exam sprint: filter "Due + Favorites" to focus on the important cards you've favorited

Tackling weak spots: filter "rating Hard" to concentrate on hard-to-remember cards

Category review: filter specific tags (such as #Formula or #ErrorProne) to review by topic

Chapter-by-chapter review: filter a specific document or color to review systematically by textbook chapter

⚠️Beginner tip: The first time, just filter "Due"—there's no need to over-filter. Once you're comfortable, try combining filters.

4.2 Re-sorting Cards¶

Tap Sort in the top-left corner of the review view to reorder cards by date added, due date, document position, text order, or randomly, to suit your personalized review needs.

Sort options:

Sort by Date Added: sorts by when the card was added to the review card deck
Sort by Due Date: sorts by the card's next review time
Sort by Document Position: sorts by the card's position in its source document
Sort by Text: sorts by the text on the card front
Random: sorts the cards randomly

💡 A Guide to Choosing a Sort Method:

Sort Method Best For Advantage

Sort by Due Date Daily review Soonest-due cards come first, as recommended by the FSRS algorithm

Sort by Date Added First review after adding a batch of cards Review new cards first and consolidate them while they're fresh

Sort by Document Position Systematically reviewing a book or chapter Reviewing in textbook order helps build a knowledge framework

Sort by Text Reviewing in alphabetical or pinyin order Good for vocabulary lists, glossaries, and the like

Random Avoiding memorizing order rather than content Shuffles the order to test your true recall

⚠️ Beginner tip: Just use the default sort (by due date)—it best matches how memory works.

5 Viewing Your Review History¶

5.1 Viewing Review History on a Card¶

After a review session, you can check the Review History and Next Review time on a review card.

Tap any flashcard, and in the card editor you'll see:

Review History: the time and choice (Again/Hard/Good/Easy) for each review
Next Review: the estimated time of your next review

💡What Review History Is For:

Understand your review frequency and memory curve

Judge whether a card's content or question setup needs adjusting

Identify which cards are your weak spots and need extra attention

6 Frequently Asked Questions¶

Q1: How many cards should I review per day?

A: The FSRS algorithm schedules this automatically. Usually it's enough to review the day's due cards; for beginners, 10-30 per day is recommended. As your number of cards grows, the cards due each day will gradually settle into a reasonable range.

Q2: What if I miss a review time?

A: No problem—FSRS adjusts automatically. At your next review, overdue cards are shown first, and the system recalculates intervals based on your actual performance.

Q3: Can I skip a card?

A: Yes. Swipe left or right to move to the next card. But try not to skip often, or it will hurt your retention. Skipped cards will still appear when they're due.

Q4: Can I quit in the middle of a review?

A: Yes. Your choices are saved automatically. The next time you enter, you'll start from the cards you haven't reviewed yet.

Q5: How do I pause reviews for a particular card?

A: Remove the card from review (see Flashcard Creation ③: Setting the Flashcard Front and Back). Removing it doesn't delete the card's content; it just cancels the review schedule.

Q6: Why do some cards have very short review intervals and others very long?

A: The FSRS algorithm adjusts dynamically based on your memory feedback. Cards you rate "Hard" or "Again" get shorter intervals, while cards you rate "Easy" or "Good" get longer intervals. This is personalized, intelligent adjustment.

7 📌 Next Steps¶

Congratulations—you've mastered the scientific way to review flashcards!

Now you can:

✅ Review efficiently with full-screen review mode
✅ Choose review intervals based on how well you remember
✅ Filter and sort the cards you need to review
✅ Use helper features like annotation and Speech

Up next, you can:

If you want to view a card's context during review to aid understanding and memory:

→Go further: Flashcard Review ②: Tracing the Source Context

Sort Method	Best For	Advantage
Sort by Due Date	Daily review	Soonest-due cards come first, as recommended by the FSRS algorithm
Sort by Date Added	First review after adding a batch of cards	Review new cards first and consolidate them while they're fresh
Sort by Document Position	Systematically reviewing a book or chapter	Reviewing in textbook order helps build a knowledge framework
Sort by Text	Reviewing in alphabetical or pinyin order	Good for vocabulary lists, glossaries, and the like
Random	Avoiding memorizing order rather than content	Shuffles the order to test your true recall