The directory is publicThis text is the Header document of the Portal. You can see it because Public is checked in Setup: otherwise, both the Header and the Class containers here would be invisible.

Populate the Portal with Class Containers: use Class Project Layouts from the Portal Toolbar to create them, and make one Project for each class in school.

Give teachers Controller and their students Reader privileges to their respective classes [each teacher and student must also be subscribed to their class]. A teacher can have more than one class, and a student can belong to more than one. Set All Users to Disallowed
 
With FirstMagic Pro, Class Containers can have their own logos, menus and skins, and teachers can merge their FirstClass Personal Sites with Class Containers seamlessly.

To get started, subscribe yourself to the example class below and log in to see how it works: classes you are subscribed to makes up your personal Home Page. If the Directory is public you also have a More link to browse [but not necessarily read] other classes.