When you select “yes” to blocking material, students can only see the Study Island topics assigned on the Class Page(s) and cannot choose other topics via the navigation bar. To block other material, just go to “Class Manager,” then click on your class name (this must be activated and have an assignment or assignments already in it) and then select “Yes” beside “Block Other Material.” Please remember that all subjects will be blocked when you select this feature, and other teachers will need to create assignments for students to access their material.