Classroom Hubs are for schools and provide additional functionality that apply to Classrooms.
First, you will have to make sure your "Organization Type" is "School" in order for your hubs to have a classroom option:
Next, to indicate that a Hub is a Classroom Hub, make sure that the Grade Level on the Hub Settings page field has a value.
Now when you view the Members Page for a Classroom hub, you will notice that the sidebar on the right shows Teachers, Teacher Assistants, Room Parents and Hub Admins. Students are listed on the left and Adults are listed on the right.
After you select one or more people using the check boxes, the People Actions menu appears. There are several actions that can be performed.