Words you miss stay in a hot orbit and come back within the same round and again tomorrow. Each time you get a word right, it drifts outward and waits longer before returning: 1 day, 3 days, a week, a month. Questions get harder as a word moves out, from recognizing it to using it in a sentence to spelling it from memory.
Why it works: the research behind each feature ▾
- Retrieval practice. Every word is met as a question, never a flashcard to reread. Pulling a word from memory strengthens it far more than restudying it.Roediger & Karpicke 2006; Dunlosky et al. 2013 rate practice testing "high utility."
- Spaced repetition. Reviews are scheduled just before you would forget, with gaps that grow each time you succeed.Cepeda et al. 2006 meta-analysis; SM-2 algorithm (Wozniak 1990).
- Pretesting. New words start with a guess before the answer is shown. Even a wrong guess primes the memory for the feedback that follows.Richland, Kornell & Kao 2009; Kornell, Hays & Bjork 2009.
- Successive relearning. A missed word returns within the same round until you get it right, then again tomorrow.Rawson & Dunlosky 2011.
- Morphological analysis. Each word shows its roots and prefixes, and the Roots explorer groups words that share them, so you can decode words you never studied.Bowers, Kirby & Deacon 2010 meta-analysis; Nagy, Carlisle & Goodwin 2014.
- Keyword mnemonics and elaboration. A memory hook ties each word's sound to its meaning; synonyms, antonyms, and two different contexts build a richer trace.Atkinson 1975; Pressley, Levin & Delaney 1982; Nagy & Herman 1987 on varied contexts.
- Generation. Writing your own sentence with a word makes you process it deeply, the strongest form of involvement in vocabulary research.Slamecka & Graf 1978; Laufer & Hulstijn 2001 (Involvement Load).
- Learning from errors and distractors. Feedback explains the right answer and what the other options meant, so every question teaches four words.Butler & Roediger 2008; Metcalfe 2017.
- Self-rating. Marking a review Hard, Good, or Easy tunes the schedule and builds the habit of judging what you really know.Dunlosky & Rawson 2012 on monitoring accuracy.
- Interleaving and rising difficulty. Reviews, new words, and question types are mixed, and each word graduates from recognition to sentence use to spelling from memory.Rohrer & Taylor 2007; Bjork's "desirable difficulties."