A short question waits on your widget. You guess, and one tap reveals the answer with the carefully checked fact behind it.
Recall before reveal is what makes things stick. The widget builds it into a screen you were going to look at anyway.
On which planets does it rain diamonds?
A question from the topics you picked, rotating on your schedule.
“Jupiter… no, Neptune?”
Say it to yourself first. Two seconds. That’s the whole ask.
Neptune and Uranus.
Crushing pressure squeezes carbon out of methane and compresses it into diamonds that sink toward the core.
Via NASAOnly the topics you switch on. New questions land every month.
Every topic opens with a free preview · another question unlocks daily
Prefer no quiz? One tap flips every widget from questions to quiet discoveries.
Questions rotate on your schedule, from every 15 minutes to every few hours.
Keep the questions that made you look twice, and revisit them any time.
No accounts, no tracking, notifications opt-in. Everything lives on your device.
Another question unlocks each day at no cost. Lock&Learn+ opens every topic at once, along with every topic we add next.
Install Lock&Learn, then touch and hold your Lock Screen, tap Customize, tap the widget area, and choose Lock&Learn. A question will wait there every time your screen wakes. There is a Home Screen widget too: touch and hold an empty area, tap the plus button, and search for Lock&Learn.
Yes. The app is free on iOS: every topic opens with a free preview and another question unlocks daily. Lock&Learn+ is an optional upgrade that opens every topic at once, offered as a yearly plan with a free trial or a one-time lifetime purchase.
Space, History, Human Body, Ocean, Psychology, Food, Animals, Planet Earth, Science, Sports, Arts and Music, and Inventions. You switch on only the topics you want, and new questions land every month.
Every question ships with the fact behind the answer, checked against reliable sources before it reaches your widget, and the reveal names where it came from.
Yes. One tap in settings flips every widget from questions to plain facts, so each glance becomes a quiet discovery instead of a quiz.
No. There are no accounts and no tracking. Streaks, saves and progress live on your phone and nowhere else, and notifications are opt-in. More in the Privacy Policy or on the Support page.