Learning vocabulary with an app: a card box for the iPhone

You probably know the flashcard box from fifth grade: card right, move one compartment forward. Card wrong, back to the start. The principle is attributed to Sebastian Leitner, and his book So lernt man lernen is documented in its fourth edition already in 1972. It still works today. It has just two weaknesses: you have to manage the compartments yourself, and all cards in a compartment get the same interval. The box doesn't know whether you never forget “la fenêtre” but do forget “le chemisier” every time.

An app like checkst essentially does what the box does, but calculates the intervals for each card individually. Here is what research actually says about learning vocabulary, and how to build a routine from it that still runs after three weeks.

Are you learning a specific language? There are dedicated pages for English, Spanish, Japanese and Latin.

What the research says

Spreading beats cramming. The meta-analysis by Cepeda et al. summarized 839 comparisons from 317 experiments: the longer you want to retain something, the larger the gaps between repetitions should be. In 2009, Kornell showed with digital flashcards that one large deck with large gaps works better than four small decks, and that distributed learning also beats cramming on the last day. The punchline: 90 percent of participants benefited from spacing, but after the first session 72 percent considered cramming more effective. Your gut feeling is misleading you.

The exact curve matters less than you might think. In 2015, Nakata had students learn 20 English-Japanese word pairs. Expanding gaps were slightly better than equal gaps, but how widely the repetitions were spread overall made the bigger difference.

How many words? For English, Nation calculated that for about 98 percent text coverage you need 8,000 to 9,000 word families for written texts, and 6,000 to 7,000 for spoken English. These are word families, not cards, and it is no guarantee of understanding. But it explains why frequency-list decks are so popular.

Which card direction?

Nation distinguishes two directions:

• Receptive: foreign word on the front, German meaning on the back. Trains understanding when reading and listening.
• Productive: German on the front, foreign word on the back. Trains using the word yourself.

Each direction mainly helps with the task it trains, with some transfer to the other. If you want to understand and speak, practice both. Not every word needs both cards: technical terms you only need to read are fine in one direction.

Sentences or single words? “Only sentences work” is an internet myth. In 2007, Webb found no significant overall difference between word pairs and words within a single sentence. In a second study, more encounters with a word in context produced more word knowledge. In practice: cards as the entry point, reading and listening as supplements.

Your workflow with checkst

1. Choose a deck. Either type in your textbook vocabulary or import a frequency deck from AnkiWeb, for example “Französisch 5000”, which is listed as a French-German deck with audio and example sentences. checkst imports .apkg files directly. Still, look closely at ready-made decks: for the “Spanish Top 5000” deck, reviews complain about inaccurate translations and unsuitable images.

2. Photograph instead of typing. Photograph the vocabulary list in your textbook, and checkst reads the text using text recognition. Or let AI suggest cards from a text, on the device or with your own OpenAI key, and strike out what you don't need.

3. Add pronunciation. checkst reads cards aloud with speech output; you set the language per field. An honest note: in a study with 216 learners, additional pronunciation recordings brought no advantage for word meaning. However, pronunciation itself was not what was measured. If you want to speak, say the answer out loud.

4. Let FSRS run. checkst schedules with FSRS, not fixed compartments. According to the Anki manual, FSRS also avoids the “ease hell” problem of the old SM-2 method, where difficult cards got stuck in endless repetitions. The target retention is set to 90 percent by default. If you didn't know a word: “Again”, not “Hard”.

5. Plan for boredom. A user on Reddit describes how more than 100 vocabulary reviews a day bored him so much that he started postponing. Keep new cards small, and use the streak and the home screen widget as a reminder so that one day off doesn't turn into a week.

Example cards

These examples use both translation directions, with German prompts or answers and a dictionary example sentence:

The second card also tests the article. Anyone who learns “chemisier” in French without “le” ends up learning it twice.

Limitations

• Cards don't replace reading and listening. They get you to the first thousand words faster. You become fluent through contact with the language.
• No ready-made checkst decks. You bring your own vocabulary or import Anki decks. We do not check their quality.
• Apple only. iPhone and iPad; no Android, no browser.