The sidebar contains the list of pages that can be used during the lessons. You first choose the course and then the list of pages is displayed.

You can search for a specific page using the text field on the top:

Search page

When you click on the name of a page on the sidebar, the page will be loaded on the teacher's computers and also on the computer of all connected students. See how to <a class="internal" href="/wiki/Connect-a-student">Connect a student</a>.