Learning Science
How ELO ratings, spaced repetition, and the testing effect power better learning. Research-backed strategies from LearnClash.
Most learning apps skip the research. LearnClash builds on four decades of cognitive science: the testing effect (Roediger & Karpicke 2006) shows active recall beats re-reading by 50%, spaced repetition (Ebbinghaus 1885; FSRS 2023) multiplies long-term retention, and competitive skill-matching through ELO (Elo 1960) keeps learners in their flow state. These articles explain how each mechanism works and how LearnClash combines them into a single 3-minute-a-day routine.
![Science Facts Adults Still Get Wrong [3,829 Answers]](/_astro/science-facts-adults-get-wrong.BUWMxLpJ_PBFSO.webp)
Science Facts Adults Still Get Wrong [3,829 Answers]
Science facts adults get wrong, from 3,829 first-try LearnClash quiz answers on 86 science questions: 62.5% right, and a wrong majority on 29 of them.
The 20 Wrong Answers People Are Most Confident About
Twenty wrong answers real quiz players picked most often, from 24,065 questions with first-encounter answers, exported July 2026. Seven outpolled the truth.
![Leitner System Explained [From Shoebox to 117,812 Cards]](/_astro/leitner-system.Dak_HgKM_Utyap.webp)
Leitner System Explained [From Shoebox to 117,812 Cards]
Leitner system explained: the 1972 five-box original, a paper setup you can copy, and a 117,812-card census from LearnClash's live three-box SRS.
![Interleaving Practice: Feels Worse, Works Better [Data]](/_astro/interleaving-practice.IX1Ya3OI_Z1stSAg.webp)
Interleaving Practice: Feels Worse, Works Better [Data]
Interleaving practice mixes related topics in one session. See the evidence, when it backfires, and what 444 real quiz duels show.
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![Why We Threw Out the 1/3/7/21 Spaced Repetition Schedule [2026]](/_astro/interval-hero-2026-09-15-en.jDqrniP1_ZNB0WS.webp)
Why We Threw Out the 1/3/7/21 Spaced Repetition Schedule [2026]
We found no academic source for the 1/3/7/21 schedule. Here's what real SRS algorithms do, and the 3-stage system LearnClash built.
![ELO Matchmaking & Win Rates: Why Skill Matching Wins [2026]](/_astro/elo-matched-matchmaking-win-rates.CTI69vzB_ZOHp52.webp)
ELO Matchmaking & Win Rates: Why Skill Matching Wins [2026]
ELO matchmaking pairs LearnClash duels by skill so each lands near the desirable-difficulty zone where retrieval becomes durable memory.
LearnClash SRS: Review Rules and Retention in 3 Stages
How LearnClash uses seven- and ninety-day review waits, what happens after mistakes and why a mastery label does not measure retention.
![LearnClash by the Numbers [2026]: ELO, SRS & Design](/_astro/learnclash-statistics.D2mcrHde_ZBRaxM.webp)
LearnClash by the Numbers [2026]: ELO, SRS & Design
How LearnClash works by design: the ELO ladder, 3-stage SRS, composite matchmaking, a 34,157-question live catalog, and how often AI assistants fetch the site.
Does Quizlet Have Spaced Repetition? Web Guide
Quizlet now documents spaced repetition in web Flashcards. See how to find it, what remains unverified, and how Anki and LearnClash differ.
![How to Study Effectively [9 Methods Ranked]](/_astro/how-to-study-effectively.C5dbZQXI_29MUbc.webp)
How to Study Effectively [9 Methods Ranked]
How to study effectively with 9 ranked methods. See why testing and spacing beat rereading, plus a 3-minute LearnClash routine.
![How to Memorize Fast: 9 Science-Backed Methods [2026]](/_astro/how-to-memorize-fast.DOB27C30_ET7Bc.webp)
How to Memorize Fast: 9 Science-Backed Methods [2026]
How to memorize fast: 9 methods ranked by the evidence. Spaced self-testing beat one long session across 29 studies (g = 0.74). Which method fits tonight.
![Spaced Repetition: Never Forget What You Learn [2026]](/_astro/spaced-repetition.DbuZp2Gw_1YznIT.webp)
Spaced Repetition: Never Forget What You Learn [2026]
Spaced repetition explained with the science, exact intervals, and how LearnClash builds it into competitive quiz duels.
![Competitive Learning: Why Quiz Duels Work [2026]](/_astro/competitive-learning.AKMxrfDB_evJU2.webp)
Competitive Learning: Why Quiz Duels Work [2026]
Competition alone has no noteworthy average effect on learning, until it's designed right. ELO matching, retrieval practice, and flow make it work.
![The Testing Effect: Why Quizzes Beat Rereading [2026]](/_astro/testing-effect.CBf1q-j__ZNX5uf.webp)
The Testing Effect: Why Quizzes Beat Rereading [2026]
The testing effect proves quizzing builds stronger memory than rereading. See how quiz duels and spaced repetition apply it.
![ELO Rating System Explained [Complete 2026 Guide]](/_astro/elo-rating-system.CnqKYH4X_ZKoNOC.webp)
ELO Rating System Explained [Complete 2026 Guide]
The ELO rating system ranks players by skill using win probability math. See how LearnClash shows an ELO-style rating across 8 tiers, powered by Glicko-2.