What Is Spaced Repetition?

Q: What is spaced repetition?

Spaced repetition is a learning technique that schedules review sessions at increasing intervals based on how well you know each item. Items you know well are reviewed less frequently; items you struggle with are reviewed more often. This exploits the 'spacing effect' — the well-documented finding that distributed practice is more effective than massed practice (cramming).

Q: What is the best spaced repetition app for language learning?

Anki is the most powerful and flexible spaced repetition app for language learning. It's free, open-source, and supports custom card formats including audio, images, and furigana. For beginners who find Anki overwhelming, Duolingo and Clozemaster also use spaced repetition in a more guided format.

Q: How does spaced repetition work with sentence mining?

Sentence mining and spaced repetition are a natural pair: you mine vocabulary from authentic content (TV shows, podcasts) using a tool like LangPanda, then review those words in Anki using spaced repetition. This creates a vocabulary acquisition loop where every word you learn comes with real-world context.

Q: How many Anki cards should I review per day?

Most language learners do best with 20–50 new cards per day and 100–200 reviews. Going above this leads to review debt that compounds quickly. It's better to add fewer cards consistently than to add many cards and fall behind on reviews.

Q: Is Duolingo spaced repetition?

Duolingo uses a simplified version of spaced repetition in its review system, but it's less rigorous than Anki. Duolingo's algorithm prioritizes engagement over optimal memory retention. For serious language learners, Anki with sentence-mined cards is significantly more effective.

Spaced repetition is the most evidence-backed vocabulary acquisition method in language learning. Here's how it works, why it works, and how to combine it with streaming immersion for maximum efficiency.

The Forgetting Curve

In 1885, German psychologist Hermann Ebbinghaus discovered the forgetting curve — the rate at which newly learned information is forgotten over time. Without review, you forget roughly 50% of new information within a day, and 90% within a week. Spaced repetition exploits the inverse of this: each time you successfully recall an item, the forgetting curve resets at a shallower slope, meaning you need to review it less frequently over time.

Active Recall

You must retrieve the information from memory — not just re-read it. This is what makes flashcards more effective than highlighting.

Optimal Timing

Review each item just before you would forget it. Too soon wastes time; too late means re-learning from scratch.

Expanding Intervals

Each successful recall extends the next review interval. A word you know well might be reviewed after 1 day, then 4 days, then 2 weeks, then 2 months.

Anki: The Gold Standard

Anki is the most widely used spaced repetition software among serious language learners. It's free, open-source, and uses the SM-2 algorithm (developed by Piotr Wozniak) to schedule reviews. The key advantage of Anki over apps like Duolingo is that you control the content — you can add words from your own immersion sources, with audio and context from the actual shows you're watching.

The Streaming + Spaced Repetition Workflow

1. Watch with LangPanda

Watch your target language content on Netflix, YouTube, or Crunchyroll with LangPanda's dual subtitles enabled.

2. Mine vocabulary

When you encounter an unknown word, click it for instant lookup. If it's worth learning, export it to Anki with one click. The card includes the subtitle sentence, translation, and audio from the show.

3. Review daily

Open Anki each day and complete your reviews. Aim for 20–50 new cards and 100–200 reviews. The algorithm handles the scheduling.

4. Encounter in context

As your vocabulary grows, you'll start recognizing mined words in new episodes. This reinforces memory through contextual re-exposure — the most natural form of spaced repetition.

Start the Workflow

LangPanda's 1-click Anki export makes the streaming + spaced repetition workflow seamless. Try it free for 7 days on your own content.

Try LangPanda Free

Related Guides

Frequently Asked Questions

What is spaced repetition?

What is the best spaced repetition app for language learning?

How does spaced repetition work with sentence mining?

How many Anki cards should I review per day?

Is Duolingo spaced repetition?

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