1. Daily Art
Exoplanets is an interactive catalogue of all the known planets we've found outside of our own solar system. Scroll through them as a list, or point your phone at the sky and use the augmented reality sky map to see what you can find.
The app is made by a professional astronomer and is updated within hours whenever new planets are announced. You can even choose to get push notifications, so you're the first to know.
Duolingo is easy and intuitive way to learn languages. Choose from Spanish, French, German, Portuguese, Italian, Dutch, Irish, Danish, and English.
The app doesn't cost you anything and instead supports itself by getting users to translate sentences while they learn (BuzzFeed has a deal with Duolingo, so you could even be translating BuzzFeed posts into other languages).
6. Night Sky
Anyone with an interest in what's going on above their heads will learn something from Night Sky. The app's star map shows you were constellations and planets are in relation to your current location (even during the day when you can't see them). It also includes satellites – very handy for International Space Station spotting.
8. Quick Maths
Quick Math does what it says it on the tin: gives you quick, simple maths tests on addition, subtraction, multiplication, and division. Draw your answer right on the screen and get through the set as fast as possible to beat your personal best.