Khan Academy

Khan Academy’s mission is “providing a high quality education to anyone, anywhere.” Its mobile app is an extension of the Khan Academy website.

Access more than 4,300 “microlecture” videos on math, history, astronomy, economics, science, humanities and more. Get downloadable videos (individual videos or entire playlists to watch offline), subtitles and progress tracking by logging in with your user account to get credit for watching videos.

Your learning syncs between your device and khanacademy.org, so your progress is always up-to-date. Exercise modules are to be added soon.

Free for iOS, Android and Windows Phone.