Favorite reference apps for multiple subjects.
Website: http://www.khanacademy.org/
Free iPad app: https://itunes.apple.com/us/app/id469863705?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/id469863705?mt=8&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=org.khanacademy.android
Free Android Tablet app: https://play.google.com/store/apps/details?id=org.khanacademy.android
Edmodo app: https://spotlight.edmodo.com/product/khan-academy,324527/
Free iPad app: https://itunes.apple.com/us/app/encyclop-dia-britannica/id447919187?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/encyclop-dia-britannica/id447919187?mt=8&at=10l6SU
Website: https://www.britannica.com/
Website: http://ed.ted.com/
Website: http://www.youtube.com/schools