There are 2 ways to view classroom assignments. You can access assignments directly from your Classes tab, or from the Assignments tab.
Access from your Classes tab:
Each classroom has several quick links. Click on "Open Assignments."
This will bring you to the Open Assignments for the selected classroom.
Access from your Assignments tab:
In your Assignments tab, the default view will show your Open Assignments for all classes. You can filter by Class, and you can change tabs to see Upcoming and Closed Assignments as well.