Go to the Classrooms page and click “Settings” next to the classroom you're interested in.
Here you can check which lessons and steps your students see.
To apply these settings to multiple classrooms, click the "apply to" tab at the top right of the page.
To apply the same settings in all units, select the boxes in the "All Units" section at the top of the page.
When you're done, scroll to the bottom and press "Save"
To assign a test, check out this article.