Google Drive
Google Docs and Google Drive allow teachers and students to share and collaborate on files. Users can use the chat function to communicate while they work together on a file—regardless of where they are. There is even a hangout add-on that allows users to communicate via webcam while working on a document. Drive stores files and allows access on any internet-equipped device, including Chromebook and Ipad, which are commonly used in classrooms.
https://www.google.com/drive/