After Students have been mass-onboarded via CSV, they must join their teacher's groups so that they can work with their teachers, in channels. Students can join multiple groups so that they may work with all of their teachers.
First, teachers should distribute the invitation code of the group they wish students to join. This can be found on the group management page. Select students in the main navigation bar, then click the gear icon to the right of the group name.
Second, students should enter this code on their own groups pages. Go to the upper right menu and select the three heads icon. On the groups page enter the code in the field on the right, and click Join.