Learn maths, biology, chemistry, economics, art history for free

"With its simple interface, the Wolfram|Alpha App lets you instantly compute answers to questions across thousands of domains—from finance and food to math and medicine to stocks and spacecraft to wordplay and weather..."

Explore math with Desmos! Plot functions, create tables, add sliders, animate your graphs, and more -- all for free.

"Official Australian statistics and more on your iPhone, iPod Touch or iPad, brought to you by the Australian Bureau of Statistics."

Numbers is a spreadsheet app for iPad, iPhone, and iPod touch. Make spreadsheets with tables, charts, photos, and graphics.

"Video Physics brings physics video analysis to iPhone, iPod touch and iPad. Take a video of an object in motion, mark its position frame by frame, and set up the scale using a known distance. Video Physics then draws trajectory, position, and velocity graphs for the object."

Learn the basics of fractions. With each new fractions lesson learnt, you’re given a mission: to build together parts of a spaceship.