The science behind VocabGecko
Plain-English answers about the research VocabGecko is built on, with full references at the end of the page.
Free beta · for children aged 8–11 · works on iPad and computer
What research is VocabGecko built on?
Four findings. FSRS, a scheduler built on peer-reviewed memory research, decides when each word comes back. Spaced practice helps children remember more than cramming. Answering questions beats re-reading. And the best gap between reviews depends on how far away the test is. Full references are at the end of this page.
The sections below take each finding in turn.
How does VocabGecko decide when a word comes back?
It uses FSRS, the Free Spaced Repetition Scheduler. FSRS gives each word three numbers: how hard it is, how long the memory is likely to last, and how likely your child is to recall it right now. It then schedules the next review for the moment that chance is predicted to fall to a target. VocabGecko aims for about 9 chances in 10.
VocabGecko marks every answer itself, so your child never has to rate how well they knew a word. A wrong answer brings the word back sooner. An answer that is right first time pushes it further away.
FSRS descends from a peer-reviewed memory model. Ye, Su and Cao (KDD 2022) built that model from 220 million learner logs from a vocabulary app, with an optimal scheduler on top of it, and reported a 12.6% improvement over the previous state of the art. FSRS is the open-source successor to that KDD model, and it shares its first author, Ye. Su and colleagues (IEEE TKDE, 2023) later published the extended journal version of the model.
One honest caveat: the specific FSRS versions VocabGecko uses are open and reproducible, but they are not themselves peer-reviewed. The peer-reviewed foundation is the KDD and TKDE memory model they build on.
Does spaced practice work for children?
Yes. In a study of young children, Vlach, Sandhofer and Kornell (Cognition, 2008) found that spaced presentation beat massed presentation for memory and for learning categories. Spacing means returning to something after a gap, rather than going over it again and again in one sitting. VocabGecko spaces every word, and lengthens the gap each time your child remembers it.
The children in that study were much younger than 11, so it shows that spacing works for children's memory in general, not at one particular age.
Is quizzing better than re-reading for remembering words?
For long-term memory, yes. Roediger and Karpicke (Psychological Science, 2006) found that retrieval practice, which means answering questions from memory, produced better long-term retention than restudying the same material. That is why every VocabGecko review is a quiz question and not a flashcard flip.
What is the best gap between reviews?
It depends on how far away the test is. Cepeda, Vul, Rohrer, Wixted and Pashler (Psychological Science, 2008), with more than 1,350 participants, found that the best review gap is about one fifth of the time until the test when the test is a few weeks away, falling to about one twentieth when it is a year away.
For an exam about ten to twelve months away, that points to gaps of about two to four weeks. So VocabGecko caps the gap between reviews at 30 days. In the final six weeks before an exam date you add, the cap drops to 14 days, so every word gets a fresh review shortly before the test.
Can VocabGecko promise better exam results?
No. No method can promise exam results, and VocabGecko cannot promise them either. Spacing and retrieval practice are among the best-evidenced ways to learn, including in children, and VocabGecko is built on them. The studies above measure how well people remember what they studied. None of them tests 11+ marks.
For the practical side, read the 11+ vocabulary guide, or see the questions parents ask.
Where can I read the original research?
Every study behind this page is listed below with its authors, year, title and venue. The two scheduling papers are in computer-science venues, and the three learning papers are in psychology journals. Search for a title to find the paper and read it for yourself.
- Cepeda, Vul, Rohrer, Wixted & Pashler (2008). Spacing effects in learning: A temporal ridgeline of optimal retention. Psychological Science 19(11), 1095–1102.
- Roediger & Karpicke (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science 17(3), 249–255.
- Su, Ye, Nie, Cao & Chen (2023). Optimizing Spaced Repetition Schedule by Capturing the Dynamics of Memory. IEEE Transactions on Knowledge and Data Engineering (IEEE TKDE) 35(10), 10085–10097.
- Vlach, Sandhofer & Kornell (2008). The spacing effect in children's memory and category induction. Cognition 109, 163–167.
- Ye, Su & Cao (2022). A Stochastic Shortest Path Algorithm for Optimizing Spaced Repetition Scheduling. KDD 2022 (ACM SIGKDD), pp. 4381–4390.
Ready to try it with your child's own words?
Join the free beta waitlist. Once you have a place, you type in the words from your next practice test and check the first cards. Joining takes about a minute. VocabGecko is free during the beta, needs no card, and works alongside the prep platform or tutor you already use.
Free beta · no card needed