It can be convenient to display certain student groups on your homepage for quick reference. This is controlled on your Groups page and occurs when two criteria are met: 1) the group is configured to show up on the homepage and 2) you have the group "starred".
Student groups can range from absent students to sports teams to intervention groups. After creating your group – and before you save it – click "Yes" for "Show a List of the Current Members on the Homepage".
This is located under the "Save Filter" section. You can also update existing groups by loading them, changing this setting and clicking "Save" (or "Save Copy" to create a new version of the group while leaving the original alone).
To make a group show up on the homepage for your others, click the gear icon next to the group and then click the "Share" button. You can choose individual users, all users, or user groups. Note that whatever notification settings are in place will get applied to others. More on that here.
If someone else created a group that you'd like to add to your own homepage, find the group in the "Existing Filters" section and star it. You'll also want to make sure that it's configured to show up on homepages in the "Save Filter" section.