Trivia Difficulty Index
Per-topic wrong rates. Three editions: the October 6 league behind table 1, the July 21 league, and the June 9 full file.
LearnClash open data
Hard Trivia Questions, Ranked by Real Miss Rates
Hard trivia questions, measured instead of guessed at. Every rate on this page comes from first-encounter answers in LearnClash 1v1 duels: 387,485 answers across 516 topics in the October 6, 2026 league, and 371 first answers behind the 8 selected question rows captured September 9. The two snapshots have different scopes and dates; they do not form a time trend. Sample size on every row.
The 50 hardest trivia topics by wrong rate
In the LearnClash Trivia Difficulty Index, a topic's wrong rate is the share of all recorded answers on that topic that were wrong. It is answer-weighted, so a question that 60 people met counts six times as much as one that 10 people met. The October 6, 2026 league ranks the 516 topics with at least 100 answers. These are the top 50, from Food Origin Myths (mythology) at 62.1% down to Frida Kahlo (artist) at 45.4%.
Where a topic has a question with 10 or more answers, its hardest one is listed under the topic name with that question's own wrong rate and sample. Those are anecdotes with small samples, not a ranking. Some topics have no question over the 10-answer line yet, so the cell stays empty rather than showing a number that wouldn't hold.
| # | Topic and its hardest question | Questions | Answers (n) | Wrong rate |
|---|---|---|---|---|
| 1 | Food Origin Myths (mythology)Hardest: Which country's 19th-century snack was the ancestor of the fortune cookie? (90.0% wrong, n=10) | 36 | 190 | 62.1% |
| 2 | The Lord of the Rings: The Rings of Power (TV series) | 30 | 103 | 58.3% |
| 3 | Play (theatre)Hardest: Why does Prospero live on the island in Shakespeare's The Tempest? (63.6% wrong, n=11) | 36 | 136 | 57.4% |
| 4 | Television (media)Hardest: What animal did Arthur Fonzarelli famously jump over in Happy Days? (80.0% wrong, n=10) | 68 | 258 | 56.6% |
| 5 | Paranormal Phenomena (subject)Hardest: What caused the 1952 Flatwoods sky sighting, in Joe Nickell's view? (100.0% wrong, n=11) | 38 | 181 | 54.7% |
| 6 | Janis Joplin (musician)Hardest: Which car did Janis Joplin have painted with psychedelic designs? (70.0% wrong, n=10) | 51 | 159 | 54.1% |
| 7 | Number Theory (mathematics)Hardest: What is the smallest number equal to the sum of its proper divisors? (90.0% wrong, n=10) | 32 | 128 | 53.9% |
| 8 | Creation Myths (mythology)Hardest: What was the sky made of in Norse creation myths? (90.9% wrong, n=11) | 24 | 137 | 53.3% |
| 9 | Reptiles (herpetology)Hardest: Which African snake is the fastest snake in the world? (58.3% wrong, n=12) | 30 | 129 | 52.7% |
| 10 | The Legend of Zelda (game) | 55 | 133 | 51.9% |
| 11 | Mountain Biking (sport)Hardest: Which California mountain is considered the historical birthplace of mountain biking? (90.0% wrong, n=10) | 27 | 103 | 51.5% |
| 12 | Mechanical Engineering (science)Hardest: Which element is the most abundant metal in the Earth's crust? (100.0% wrong, n=13) | 373 | 2,116 | 51.4% |
| 13 | Renaissance Art (art movement)Hardest: Michelangelo carved his massive David from what kind of marble block? (54.5% wrong, n=11) | 38 | 214 | 51.4% |
| 14 | Deductive Reasoning (logic)Hardest: In logic, 'If P then Q' is logically equivalent to which expression? (80.0% wrong, n=10) | 39 | 403 | 50.9% |
| 15 | Marie Curie (physicist)Hardest: How did Marie Curie's husband Pierre die in 1906? (72.7% wrong, n=11) | 25 | 136 | 50.7% |
| 16 | Porsche History (automobile manufacturer)Hardest: Why did Ferry Porsche decide to build his first sports car? (70.0% wrong, n=10) | 53 | 194 | 50.5% |
| 17 | Mobile Legends Lore (gaming) | 49 | 111 | 50.5% |
| 18 | Internet Memes (pop culture)Hardest: Why did Grumpy Cat always appear to be frowning? (72.7% wrong, n=11) | 32 | 230 | 50.4% |
| 19 | Numerology (mythology)Hardest: What tree connects the nine worlds in Norse mythology? (50.0% wrong, n=10) | 39 | 152 | 50.0% |
| 20 | The Quran (religious text) | 88 | 249 | 49.8% |
| 21 | AC/DC (band)Hardest: What did the Young brothers consider doing after Bon Scott's death? (72.7% wrong, n=11) | 65 | 381 | 49.6% |
| 22 | Pirates and Privateers (history) | 50 | 117 | 49.6% |
| 23 | Colonization of Mars (space exploration)Hardest: What was the first US lander on the surface of Mars? (80.0% wrong, n=10) | 52 | 222 | 49.5% |
| 24 | West Coast Hip Hop (music genre)Hardest: What style of oversized pants did MC Hammer make famous? (20.0% wrong, n=10) | 38 | 170 | 49.4% |
| 25 | Pepe the Frog (meme)Hardest: Which emotion do the Pepe-based 'monka' emotes express in Twitch chat? (81.8% wrong, n=11) | 65 | 446 | 49.1% |
| 26 | Quantum Physics and Philosophy (interdisciplinary) | 24 | 106 | 49.1% |
| 27 | Green Day (band) | 43 | 182 | 48.9% |
| 28 | Padel (sport) | 32 | 118 | 48.3% |
| 29 | Philippines (country) | 49 | 136 | 47.8% |
| 30 | Human Biology (biology)Hardest: Why do veins appear blue under healthy human skin? (60.0% wrong, n=10) | 97 | 284 | 47.5% |
| 31 | Epistemology (philosophy)Hardest: What type of problem challenges the 'justified true belief' definition? (81.8% wrong, n=11) | 95 | 332 | 47.3% |
| 32 | 1990s Rock Drummers (music) | 64 | 165 | 47.3% |
| 33 | Sherlock Holmes (literary character)Hardest: What does Watson call Holmes's favourite weapon in The Six Napoleons? (92.9% wrong, n=14) | 76 | 580 | 47.2% |
| 34 | Opera (art form)Hardest: Why does Canio kill his wife during the opera Pagliacci? (63.6% wrong, n=11) | 84 | 246 | 47.2% |
| 35 | Sociology (subject)Hardest: What happens when a false definition of situation becomes true? (60.0% wrong, n=10) | 62 | 317 | 47.0% |
| 36 | Physical Exercise (health)Hardest: Which competitive swimming stroke is generally considered the slowest? (90.9% wrong, n=11) | 32 | 177 | 46.9% |
| 37 | Agatha Christie (author)Hardest: What expensive jewelry is stolen from Linnet Ridgeway in Egypt? (85.7% wrong, n=14) | 289 | 1,267 | 46.9% |
| 38 | Aptitude Tests (education)Hardest: How many points make up the highest possible composite score on the ACT? (40.0% wrong, n=10) | 38 | 148 | 46.6% |
| 39 | Volleyball (sport)Hardest: Why was volleyball invented in 1895? (61.5% wrong, n=13) | 30 | 133 | 46.6% |
| 40 | Perfume (novel)Hardest: Which of Grenouille's victims was the very first he murdered? (41.7% wrong, n=12) | 39 | 153 | 46.4% |
| 41 | Rolex (watch brand)Hardest: Which model allows the wearer to track three different time zones simultaneously? (80.0% wrong, n=10) | 37 | 128 | 46.1% |
| 42 | Biblical History (history) | 37 | 122 | 45.9% |
| 43 | Celebrity (pop culture)Hardest: Which animal did actor Christopher Walken tame in a circus? (36.4% wrong, n=11) | 34 | 133 | 45.9% |
| 44 | BookTok (social media) | 46 | 157 | 45.9% |
| 45 | Nikola Tesla (inventor)Hardest: In which Austrian city did Nikola Tesla study engineering? (80.0% wrong, n=10) | 78 | 733 | 45.8% |
| 46 | Personality Psychology (psychology)Hardest: What physical clue led doctors to first discover Type A behavior? (83.3% wrong, n=12) | 38 | 127 | 45.7% |
| 47 | German Feminism (sociology) | 186 | 412 | 45.6% |
| 48 | Classic TV (entertainment)Hardest: What TV concept did I Love Lucy accidentally create? (69.2% wrong, n=13) | 44 | 180 | 45.6% |
| 49 | Academy Awards (film award)Hardest: What were Oscar statues made of during World War II metal shortages? (60.0% wrong, n=10) | 36 | 123 | 45.5% |
| 50 | Frida Kahlo (artist)Hardest: At La Casa Azul, Frida Kahlo kept a pet named Granizo of which species? (72.7% wrong, n=11) | 163 | 454 | 45.4% |
Full league of 516 topics in the October 6, 2026 CSV. The topic pages behind these rows are playable: pick any topic in the app and the duel draws from the same question pool.
Which selected questions had the lowest correct share?
This table ranks only the editorially selected September examples, each with at least 30 counted first-encounter answers. The lowest correct share in this small selection belongs to "Why do stars twinkle when viewed from Earth?": 9.7% correct across 31 first answers, with 25% as the model baseline for uniform guesses across four options. The 8 below run from 9.7% to 33.3% correct.
Read the rates as measured with the correct answer on screen. Every one of these was answered in a four-option duel round, so the player could recognize the answer instead of recalling it. Asked open-ended at a quiz night, the task changes. These data do not measure the size or direction of that change for each question. Ties on correct share are broken by the larger sample, then by file rank.
| # | Question | Correct answer | Correct | n | Topic |
|---|---|---|---|---|---|
| 1 | Why do stars twinkle when viewed from Earth? | Air turbulence bends their light rays | 9.7% | 31 | Astronomy (science) |
| 2 | Why is Pluto not considered a planet anymore? | It failed to clear its orbit | 20.0% | 30 | Astronomy (science) |
| 3 | Why do we see halos around the Moon sometimes? | Ice crystals refract moonlight | 22.6% | 31 | Astronomy (science) |
| 4 | Which insect is the strongest relative to its body weight? | Dung beetle | 24.6% | 61 | Animals (nature) |
| 5 | Who coined the scientific name 'Dinosauria' in 1842? | Richard Owen | 26.4% | 53 | Dinosaurs (paleontology) |
| 6 | What colors can dogs see besides black and white? | Yellow and blue | 29.7% | 64 | Animals (nature) |
| 7 | What does the Greek name for squirrel mean? | Shadow tail | 31.0% | 71 | Animals (nature) |
| 8 | What did Galileo see on Venus like the Moon? | phases | 33.3% | 30 | Astronomy (science) |
Which wrong answer those players picked instead, and the sources used to check these examples, are on the common misconceptions page. The separate hardest trivia questions bank uses historical examples, not this September selection.
Why these questions are hard
The LearnClash counts describe answers given with multiple-choice options on screen. Wrong options are selected from a larger distractor pool, so two encounters need not show the same choices. A concentrated wrong answer may reflect a familiar story, a knowledge gap or unclear wording. These aggregates cannot distinguish those causes or measure confidence. Before reusing a row, inspect the exact question and answer, its source and its sample size. The current question cut contains reviewed examples chosen from rows where one wrong option led. It is not a ranking of every question in the app; selection and small samples limit interpretation.
Methodology, floors, and downloads
Both datasets are read-only exports of the LearnClash production database. The files linked here are the bytes the tables were rendered from. This page is the canonical home; the Kaggle pages are mirrors of the June difficulty file and the July misconception file.
What a first-encounter answer is
The current counter contract records eligible first SRS encounters through the duel pipeline, excluding timeouts, information-assisted joker answers (50:50, Peek and Crowd) and web-play replays. Double Down remains eligible. Under the current write contract, human-side answers in AI-rival duels can contribute; standalone Solo does not write this question-level counter. Answer keys are content-version scoped, while first-encounter eligibility follows the separate meaning-change history. A content-version change does not necessarily reset that history. This source review describes today's contract, not verified enforcement for every event in the historical files.
The topic league sums recognized answer counts across content versions. The Misconception Index selects current-version counts and excludes rows whose version had to be inferred. The export dates are capture dates for cumulative counts, not observation windows. Per-answer dates, confidence, language-specific groups, option impressions and distinct people across rows are not available. These snapshots cannot establish a time trend or a population estimate; the sample consists of recorded LearnClash app answers; distinct people cannot be counted.
Topic league (table 1)
- Source: 516 topics with at least 100 answers in the LearnClash league of 2026-10-06, 387,485 answers in total. The wrong rate is answer-weighted: wrong answers divided by all answers on the topic.
- Floor: 100 answers per topic; the hardest-question annotation needs 10 answers on that question and is shown with its own n.
- The June 9, 2026 file is the first public edition: all 570 topics, 80,553 answers, overall wrong rate 43.5%, 156 topics flagged qualified_for_league. It is the version mirrored on Kaggle.
Hardest questions (table 2)
- Source: the LearnClash Misconception Index, captured 2026-09-09. The scan read 968 public topic records and hit its 40,000-question cap after 21 of 33 topic-query batches. Of 495 machine-eligible rows, 16 had a wrong option leading; 8 survived editorial review. These selected rows contain 371 counted first-encounter answers.
- Floor: 30 first-encounter answers per question. The September cut excludes ambiguous or unsupported questions and retains exact wording and counters. The curation record documents inclusions and exclusions.
- Ranking: lowest correct share first. This ranks only the selected examples. Small samples make rankings unstable. The sample column gives context; a fixed margin rule cannot establish which questions differ reliably.
Licence and citation
CC BY 4.0. Cite as "LearnClash Trivia Difficulty Index, October 2026, Pluxia GmbH (learnclash.com)" or "LearnClash Misconception Index, September 9, 2026 curated sample, Pluxia GmbH (learnclash.com)", with a link to this page. Aggregates only; neither file contains user-level records.
Misconception Index
Per-question first-encounter shares with the most-picked wrong answer and a p-value per row.
Questions, corrections, or a request for a cut this page doesn't show: admin@learnclash.com. Press facts and logos are on the press page.
Try the hardest topics in a duel
LearnClash is 1v1 trivia on any topic, with a skill-matched opponent and a fact after every answer. The questions above come from the same pool your duels draw from. Free on iOS and Android, in English, German, French and Spanish.
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