We have had some request for a quick how-to video of rolling content from Blackboard to Canvas, and while this may not be the best method, here is the requested tutorial. The Circles team recommends you chat with a Faculty Developer/Instructional Designer (FDID) to see what strategies will work best for rolling your content. However, there is no harm in jumping in and giving it a try. You can always reset the course if you don’t like the way it looks.
See also this handout by Rick Snyder walking through the steps of exporting your Blackboard course to a zip file and importing it into Canvas: Best Practices for Migrating Content from Blackboard to Canvas.
This other document from OEI California also details the differences between Blackboard and Canvas, as well as alternatives for tools that are in Blackboard but not Canvas, such as the blog and journal tools.