"I went through the word list three times and still don't remember them." If you have studied vocabulary, you have probably been there. The cause is not the number of passes. It is the intervals between reviews and the way you review.
Vocabulary is one of the subjects most exposed to the forgetting curve. Each word stands alone with little context to help, and you start forgetting the moment you learn it. That is exactly why designing the review timing alone changes the outcome so much.
Intervals for a word: next day, 3 days, 1 week, 2 weeks, 1 month
Memory is lost fastest in the first day after learning (the forgetting curve). So the first review goes on the next day. After that, each review extends how long the memory holds, so the intervals widen.
- 1st review: the next day
- 2nd: 3 days later
- 3rd: 1 week later
- 4th: 2 weeks later
- 5th: 1 month later
The reasoning behind the widening is explained in the spaced repetition article. The numbers do not need to be exact. What the research shows is how robust the principle is, recall at expanding intervals as you start to forget, and being a day off changes nothing.
Don't "make passes" through a word list. Come back to it on its review days.
A goal like "three passes" says nothing about the gap between the first and second pass. If the first pass takes two months, the words from the start are nearly gone by the time the second pass arrives. Managing by review day for each word (or each page), not by number of passes, is what fits the forgetting curve.
The unit can be a spread or a section, not a single word
Tracking a review day for every single word is possible in a flashcard app, but not realistic with a paper word list. So make the unit bigger.
- Treat one two-page spread or one section (20 to 50 words) of the list as a unit
- When you learn that section today, set its review days for the next day, 3 days, 1 week, 2 weeks, and 1 month later
- On a review day, cover the meanings and test whether you can say them for every word in the section
A bigger unit does not reduce the effect. In a 2009 experiment, Kornell found that working through flashcards as one large stack, which spaces each word out more widely, produced higher scores later than splitting them into small stacks and drilling each intensively. "A few words, intensively" feels better right afterward, but loses to spacing over the long term.
Review by covering and recalling. Don't just look
The easiest way to waste time on vocabulary is reviewing by looking at the word and its meaning side by side. Looking creates a feeling of "I know this," but you only know it because it is in front of you. On a test, it does not come out. That is the "looks familiar" state.
Always review by covering the meaning and recalling it yourself.
- Word to meaning: see the word, say the meaning (for reading)
- Meaning to word: see the meaning, say the word (for writing and speaking; harder, and more effective)
- A word you recalled is done. Only for words you could not recall, reread the example sentence
In a 2006 experiment by Roediger and Karpicke, the group that took recall tests outperformed the group that repeatedly reread by a wide margin one week later. Vocabulary is no different. The moment you fail to recall a word is the review that does the most for that word.
Fix your daily new words at an amount you can sustain
The single most important thing for keeping reviews going is to keep the number of new words per day constant.
Learn 100 words today, and 100 words' worth of reviews come back tomorrow, in 3 days, and in a week. Push far ahead on a motivated day, and a few days later 300 words of reviews land at once. That is where it stops.
A good target is 20 to 30 new words a day (or one section a day if you work by section). At that rate, even with five rounds of reviews overlapping, you cover and recall 100 to 150 words a day, which takes 15 to 20 minutes. It may feel slow, but not stopping is faster in total.
Dealing with words that won't stick
For words you just cannot remember, adding retrieval cues works better than adding more reviews.
- Learn the example sentence with the word. Context gives you more ways to recall it
- Break it into roots, prefixes, and suffixes (un-, -able, -tion). Tie it to parts you already know
- Say it out loud. Linking spelling and sound lets you recall it from either side
These are ways to make a word easier to remember, not a substitute for review. Add the cues, then keep practicing recall on the review days.
When the exam is close
Right before TOEIC, IELTS, or a vocabulary-heavy exam, there is no time to cycle every word evenly. Prioritize.
- Start with the high-frequency words (the front of the list, or the basic level in a graded list)
- Words you have recalled at least once can go on a wider interval in the final stretch (a week untouched will not hurt much)
- Concentrate your time on the words you have never recalled
The shorter the time to the exam, the tighter the review intervals, as the research shows (Planning reviews backward from your exam date). In the final week, look only at the words you could not recall, every day.
Summary
- Manage vocabulary by review day, not by number of passes. Next day, 3 days, 1 week, 2 weeks, 1 month is the guideline
- The unit can be a spread or a section, not a single word. One large stack at wider intervals retains better (Kornell, 2009)
- Review by covering and recalling. Looking only builds "looks familiar"
- Fix your daily new words (20 to 30). Bursts pile reviews up a few days later and stop you
- For words that won't stick, add cues (example sentences, roots, saying them aloud) rather than more reviews