Oppia is a new cloud-based authoring tool under development by a team of collaborators including Google employees. Currently in beta and due for release in February 2015, Oppia is free and open source, easy-to-use and flexible. It is built around learning activities which it calls ‘explorations’. It is good at parsing answers to open questions and branching based on the user’s response and so could be very useful for learning scenarios. Open answers are also particularly useful in getting students to think about a problem at the start of a learning activity.
Oppia is quite powerful and can analyse user-created graphs, mathematical, statistical and python code problems and includes Google map integration. It can store images up to 1 MB. Plans for including audio are under consideration. At present, embedded movies must be hosted on YouTube but it can link to movies hosted elsewhere.
By the way, Oppia means learn in Finnish!