To limit the instructor role to only viewing their classes, you will need to reach out to Support to enable the can_view_instructing_classes permission. This limits the role to only being able to see the classes that they are instructing or substituting.
If both can_view_reservations and can_view_instructing_classes permissions are enabled, the role can see all classes in locations it has access to.
Please note that in order to see the roster, the instructor role will need to have the can_view_users permission enabled as well. This will also allow the role to view all users in the locations they have access to.
The can_view_instructing_classes permission applies to both Admin and Biz.