Please note that the homeroom teacher needs to be assigned first, and then the Homeroom can be configured to its group:

  1.  Click on Admin at the top of the page.
      
  2. Under Manage Groups, click Edit Groups. 
  3.  Click All Groups
  4. Next to the needed group, click Admin
  5.  Click Configure Group
  6. Under Homeroom (Optional), select the Homeroom for that group
  7. Click Update