Knowledge has an expiration date.
UNLEARN is a growing library of the things textbooks got wrong — facts that schools confidently taught generations of students, only to be quietly overturned, retracted, or refined.
Some are famous. Pluto isn’t a planet anymore. We use more than 10% of our brain. Columbus didn’t discover anything.
Most aren’t. The Stanford Prison Experiment was scripted. The marshmallow test mostly measured how rich your parents were. The amyloid hypothesis behind 30 years of Alzheimer’s research may have rested on fabricated data. Gold doesn’t come from exploding stars; it comes from colliding neutron stars. Hindenburg burned because of its paint, not its hydrogen.
You probably learned at least a few dozen things in school that aren’t true anymore. The point isn’t to feel cheated. The point is that this is normal — and it’s still happening.
Enter the year you graduated high school. The site shows you a personalized list of facts that were standard textbook material when you were in class, but have since been revised in mainstream education or scholarship.
Each fact has a brief citation — the study, journal, institution, or scholar that overturned it. None of this is hidden knowledge; it’s mostly just slow news.
Hundreds of curated entries across biology, anatomy, medicine, history, astronomy, physics, chemistry, psychology, nutrition, sports science, geography, language, food, art, technology, math, economics, and more.
Explore the full browse view, try the quiz, scroll the timeline, or check the stats.
This is not a contrarian site. It only lists things with strong, mainstream-academic acceptance that the old claim was wrong. Political controversies, fringe theories, and unresolved debates aren’t included.
It’s also not a takedown of teachers. Most taught what their own textbooks said. The textbooks were a few decades behind the research. The research itself sometimes turned out to be wrong, too.
Years are approximate. “Year debunked” means roughly when the correction entered mainstream education or general scientific consensus — not the first paper to suggest it. Reasonable people can quibble with a date by a decade or two.
Found something that’s itself outdated, mischaracterized, or worth adding? Open an issue or PR on GitHub.
Built and curated by rxxusp. Aesthetic stolen from every chalkboard you ever stared at.