Wonderlet
Wonderlet answers a simple question every day, on the topics you pick. Read today's and try the quiz.
Why does ice float?
Almost everything shrinks as it gets colder. Water doesn't: when it freezes, its molecules lock into a hexagonal lattice full of empty space. The same amount of water ends up taking more room, and its density drops by about 9 percent.
Anything less dense than the liquid around it floats. That's why ice cubes bob at the top of your glass and why lakes freeze from the surface down, not from the bottom up.
One notion a day, on your topics. About a minute.
Two or three questions for each notion, with a streak of consecutive days.
Find it again in Saved, with search by topic.
Why does ice float?
Almost everything shrinks as it gets colder. Water doesn't: when it freezes, its molecules lock into a hexagonal lattice full of empty space.
Source: Water Density - U.S. Geological Survey
Pick what makes you curious: the daily notion comes from there.
Notions come in Italian and English. You choose which to read.
Suggest what you'd like to know: we review it.
Profile
One a day, at the time you choose, from your phone. No push notifications.
Start right away. Connect one later to keep your streak and saved notions on another phone.
With Keeplet the notion becomes a flashcard to review.
With your Keeplet account the notion becomes a flashcard, and the Keeplet app brings it back when you're about to forget it. Discover Keeplet.
Question
Why does ice float?
Answer
Because water expands as it freezes: ice is less dense (0.92 g/cm³) than liquid water.
Soon, on the App Store and Google Play.
Not to start. Connect one later, with Apple, Google or email, to keep your streak and saved notions on another phone.
Yes: today's notion and the next ones are already on your phone, once you've opened the app at least once.
Every notion cites its source, at the end of the text.
Yes, up to two extra notions a day with “Another”. They don't count toward your streak.
Yes, from Today. Every suggestion is reviewed before it becomes a notion.
Italian and English.
About a minute. Each notion shows its reading time.
iPhones with iOS 16 or later and Android phones with Android 7 or later.
Yes, whenever you like, from your Profile. You can choose from fifteen topics, from Science to Law and rights.
Yes, from your Profile. It's a local reminder, one a day at the time you choose, with no push notifications.
Each notion has two or three questions, multiple choice or true or false. Every answer comes with an explanation.
It's the number of consecutive days you read the daily notion, by 11:59 PM. The daily notion's quiz adds one extra point. Miss a day and the streak starts again.
The ones you read are in History, and the ones you like are in Saved, with search by topic.
Yes, with the Share button on the notion.
Under each notion you can say whether it was useful or unclear, and add a reason if you like.
No. You only need Keeplet if you want to turn notions into flashcards to review.
In the app: Profile, Delete account. Your streak, saved notions and suggestions are deleted for good. Without the app, follow the account deletion instructions.
The full list and the reasons are in the privacy policy.