Virtual classroom with Ideaink - Ideaink allows multiple people to collaborate on a blackboard much like Google Docs allows multiple users to edit a document at once. In fact, it uses a lot of Google's real-time technology to handle such behaviors. The website can be found at https://www.ideaink.org/   At present it works only on computers. Mobile version is currently unsupported.  Works best with Google Chrome. Try it out today! Its Free!!!!!