Website: http://www.instagrok.com/
Free iPad app: https://itunes.apple.com/us/app/instagrok/id777873941?mt=8&uo=4&at=10l6SU
Google Apps for Education app: https://www.google.com/enterprise/marketplace/viewListing?productListingId=17789+13349884249762973052
Google Chrome app: https://chrome.google.com/webstore/detail/instagrok/flonaffkffjppejcafgpdgilebfikemd
Edmodo app: http://www.edmodo.com/publisher?uid=7493337