Spaced Repetition for Language Learning
You learned twenty words yesterday and today half of them are gone. That is not a discipline problem; it is how memory works, and spaced repetition is the fix: a schedule that reviews each word at growing intervals, concentrating your effort on the memories that still need it. This guide explains the science, the Leitner system behind it, and the 1/3/7/21 day schedule built into NextLang vocabulary.
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Why Cramming Fails
Ebbinghaus mapped the forgetting curve in 1885, showing that forgetting is fastest soon after learning and then slows down. A modern replication reproduced the broad shape of that curve. Murre & Dros, 2015 (PLOS ONE)
A cramming session feels effective because everything is fresh while you study. But fluency with a word you saw two minutes ago says nothing about whether you will recall it next week at a ticket counter. The forgetting curve drops fast, and one long session gives every word exactly one chance to survive it.
Reviews change the shape of that curve. Each time you successfully recall a word, its memory trace decays more slowly, which means the next review can wait longer. Spacing is not about studying more; it is about placing the same effort where it compounds.
How Spaced Repetition Works
A major meta-analysis covering 317 experiments found a reliable advantage for distributed over massed practice, and found that the useful gap between reviews grows with how long you need to remember the material. Cepeda et al., 2006 (Psychological Bulletin)
Look at 'la biblioteca', say the translation out loud, and only then flip to check.
Once a word is encoded well enough to recall at all, extra reviews are worth more spread across days than packed into tonight.
A word you have recalled several times running can tolerate a much longer gap than one you keep missing.
Hesitating for two seconds and then getting it right is a better workout than answering on reflex.
A word you need for a trip next month and a word you want for life do not deserve the same schedule.
Three misses in a row on the same word usually means the card tests two things at once, not that you need more grit.
Repeated studying wins on a test taken minutes later, which is exactly why cramming feels like it works. On delayed tests the result flips: the group that practised retrieving the material remembered substantially more. Roediger & Karpicke, 2006 (Psychological Science)
The Leitner System
The simplest way to run spaced repetition is the Leitner system, popularized by Sebastian Leitner in the 1970s for paper flashcards. The idea is only three rules: every word lives in a numbered box, a correct answer moves it up a box where reviews are further apart, and a miss drops it back to the start. The boxes and their intervals are a design choice, not part of the method. Five boxes with these gaps are what NextLang uses for vocabulary:
New words and anything you just missed. They stay in rotation until you get them right.
You recalled the word once. See it again tomorrow to confirm it survived the night.
Two successful recalls. The memory is forming, so the gap stretches to a few days.
Three in a row. A weekly check is enough to keep the word alive.
Mastered. The word counts as learned and only returns every three weeks for maintenance.
The demotion rule is what makes the system honest. A word you failed after three weeks clearly was not mastered, so it restarts the climb. The rules stay simple: one correct or incorrect decision per card moves the word through the whole schedule, with no formulas to tune.
A Schedule That Sticks
Common Mistakes to Avoid
Marking words as known out of optimism
A false positive moves the word further along the schedule before the memory is ready for the gap. When in doubt, rate it as still learning.
Cramming once a week instead of short daily reviews
Massed practice produces strong short-term performance and weaker delayed retention. Spread the same total time across the week and far more of it survives.
Only ever recognizing, never recalling
Passively confirming 'yes, I've seen this' is not retrieval. Cover the answer, produce it, then check.
Resetting the whole deck after a pause
Missing a week does not erase your progress. Resume where the schedule left off and review honestly; the words you truly forgot move back to shorter intervals as you miss them.
Adding fifty new words a day
Every new word is a future review. Add new words at a rate your review queue can absorb, and if the due count is already growing, cut the new ones before anything else.
Spaced Repetition Built Into NextLang
Your NextLang vocabulary runs a five-box Leitner-style schedule for you. Save words while studying generated flashcards or add them by hand, then open a dictionary and press Study: rate each word with Got it or Still learning. A correct answer moves the word up through the 1-, 3-, 7- and 21-day intervals; a miss sends it back to the first box for another same-day review. Prefer Anki or Mochi? Every generated deck exports to their native formats, so their schedulers pick your cards up too.
Ready to Make Your Vocabulary Stick?
Save words from any NextLang deck to My Vocabulary. Due reviews come back on their own, on the built-in five-box schedule, and studying them costs no credits.
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