Free iPad app: https://itunes.apple.com/us/app/pearl-diver-hd/id364617763?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/pearl-diver/id337567843?mt=8&at=10l6SU
Website: http://mathsnacks.com/pearl-diver-en.html
Website: http://www.ixl.com/
Website: http://play.centerforgamescience.org/refraction/site/
Free iPad app: https://itunes.apple.com/us/app/showme-interactive-whiteboard/id445066279?mt=8&uo=4&at=10l6SU
Website: http://www.showme.com/