Please use the Power BI Community Forum to discuss about materials in this course. We have created an edX specific forum, so that you can ask questions, give feedback, or just hang-around your "classmates".
The forum is located here: http://community.powerbi.com/t5/EdX-Specific-Training-Discussion/bd-p/EdXTrainingForum
You will need to create an account with Power BI Community site. I apologize for this inconvenience, but I hope the access to the community as well as the Power BI team in the forum will surpass this slight trouble.