I really like the concepts of your lesson plan. I like how the students have to take into consideration different readings and ideas to form their opinion. Opinion/Argument writing is a huge part of the Common Core State Standards and I think this lesson does a great job supporting that.
I think a way you could extend this lesson plan is to give them a scenario, maybe in groups, and have them decide what they should do to take action/form an opion about the scenario.
You might also want to insert a link to your Edmodo page so that it can be easily accessed and people can get an example of what you are using in your class.