Unless you are blessed with a large salary for a light teaching load, at some point it will become necessary to support more than one class within your site. In Drupal, courses can be organized as teacher-centered groups, or as less-hierarchical learning communities. Moreover, by creating different types of groups, we can support both types of learning within the same site.
In Drupal, group functionality comes with the Organic Groups module. This module, along with related modules that extend its functionality, allow us to set up focused workspaces within a website.