Read the statement and decide: O if it is true, X if it is false. Every answer comes with a short explanation of why, so even a wrong guess teaches you something. 500 questions in ten subjects.
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Take a short break
Press Next to continue — a short ad will play first, then the next question appears. Your progress is saved.
How to play
Pick 20, 50, 100 or 500 questions. Tap O (true) or X (false) — or press O / ← and X / → on a keyboard, then Enter for the next question. Short challenges draw the same number of questions from each subject and favour ones you have not seen recently. The 500-question challenge uses every question, pauses for a break after each 100, and saves your progress in this browser so you can resume later.
Why true-or-false is harder than it looks
With only two choices, a pure guess is right half the time, so it is tempting to think an OX quiz is easy. In practice the hard part is not choosing between two buttons but noticing which single word makes a statement wrong. "Bats are blind" and "Most bats can see" differ by a few letters and have opposite answers. A good true-or-false question is built around exactly that kind of detail: a number that is slightly off, a cause swapped for an effect, or a belief so familiar that nobody stops to check it.
That is why this quiz always shows an explanation, whether you were right or not. A correct guess with the wrong reason is still a gap in what you know, and a wrong answer is far easier to remember once you have read the one-line reason behind it. Many statements here are popular myths on purpose — the kind of thing people repeat confidently — because those are the facts most worth correcting.
Ten subjects, fifty questions each
The 500 questions are split evenly across science, the human body, animals, geography, space, history, everyday life, food, words and numbers, and sports and the arts. The statements are written to hold true anywhere in the world rather than depending on one country's school curriculum, and the same 500 questions appear in English, Korean and Spanish, so you can compare scores with friends who play in another language.
Short challenges draw the same number from every subject — two each in a 20-question round, five in 50, ten in 100 — so one strong subject cannot carry the whole score. The results screen then breaks your score down by subject, which is the quickest way to see where your general knowledge is solid and where it is thinner than you thought.
The 500-question challenge
The full challenge asks every question once, in an order shuffled so that each block of 100 still mixes all ten subjects. After every 100 questions you get a break screen with your score for that stretch and your running total. Progress is saved in this browser after each answer, so you can close the tab, come back later and pick up from the same question.
Read the whole sentence before answering. Words such as "all", "never", "only" and exact numbers are where most false statements hide.
Read the explanation even when you were right. It often adds the detail that makes the fact stick.
Review the missed list at the end. Going over only the questions you got wrong is the fastest way to turn a 70% round into a 90% one.
It is a true-or-false quiz: you read a statement and answer O if it is true or X if it is false. The format is especially popular in Korea and Japan, where O and X are the everyday marks for right and wrong.
How many questions are there?
500 in total, 50 in each of ten subjects. You can play a 20, 50 or 100-question challenge drawn evenly from every subject, or the 500-question challenge that uses all of them.
Will I see the same questions every time?
Short challenges remember which questions you have already seen in this browser and serve new ones first. Once a subject has been mostly covered, its questions are reshuffled and start again.
Can I stop the 500-question challenge and finish later?
Yes. Your position, score and missed questions are saved in this browser after every answer. When you come back, a Resume button appears above the challenges. Clearing your browser data or using a private window removes the saved progress.
Why is there a break every 100 questions?
500 questions is a long session, so the challenge pauses after each 100 to show how that stretch went. When you press Next, a short ad may play before the quiz continues; it is what keeps the site free.
Where do the facts and explanations come from?
Each statement was written around a widely documented fact and checked against standard reference sources, and questions whose answer depends on definitions or is still debated were left out. If you think an answer is wrong, let us know through the contact page.
Can I play with the keyboard?
Yes: press O or the left arrow for true, X or the right arrow for false, and Enter to go to the next question.