There are many sites that offer open or free resources to the public.
If it is open you can use and edit to make it your own as long as you give credit.
If it is free you can use it but not edit it and still have to give credit.
Website: https://www.accredible.com/
Website: https://www.class-central.com/
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/
Website: http://www.ted.com/
Free iPad app: https://itunes.apple.com/us/app/ted/id376183339?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/ted/id376183339?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.ted.android
Website: http://www.youtube.com/education
Website: http://www.ck12.org/
Free Android Phone app: https://play.google.com/store/apps/details?id=org.ck12.app.practice
Free Android Tablet app: https://play.google.com/store/apps/details?id=org.ck12.app.practice
Google Chrome app: https://chrome.google.com/webstore/detail/ck-12/ilmbnmigihncgeckjgmkehcgkdeohkhl
Free iPad app: https://itunes.apple.com/us/app/ck-12-free-fun-way-to-learn/id909343639?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/ck-12-free-fun-way-to-learn/id909343639?mt=8&at=10l6SU
Website: https://www.coursera.org/
Website: http://www.oercommons.org/
Website: http://search.creativecommons.org/
Website: http://exchange.smarttech.com/
Website: http://www.flickr.com/
Website: https://www.edx.org/
Website: http://ocw.mit.edu/
Free iPhone app: https://itunes.apple.com/us/app/mit-opencourseware-lecturehall/id379390362?mt=8&uo=4&at=10l6SU
Website: http://open.ubc.ca/