I found a solution for giving a teacher a view on a specific part of a theme. It can be achieved by using a system-context view capability for the teacher and adding this to the specific part of the theme. And then give the teacher a global role (system wide). You have to check the permissions for this role then thoroughly, so that this role doesn't get unwanted permissions. It's a specific workaround, Moodle doesn't seem to have better functionality to achieve this kind of things.