This application allows you to “learn almost anything for free” with a series of more than 4,200 educational videos on a wide range of topics from the Notation of Basic Geometry to Fiscal Cliff tutorials. The Khan Academy series also includes additional material for different subject areas (e.g. chemistry, algebra, SAT prep) that can be downloaded from the Apple and Android app stores.
Recommended ages: Middle school and up
Compatibility: iPhone, iPad, and Android
Cost: Free