Apps to help build vocabulary, spelling, definitions, etc.
Free iPhone app: https://itunes.apple.com/us/app/word-joust-for-6-8/id465179802?mt=8&uo=4&at=10l6SU
Google Chrome app: https://chrome.google.com/webstore/detail/word-joust/jijjjopeepgneiiamhahbmlnhcomdbml