Associating groups with a Moodle forum consists of two parts. The first step is to configure the forum to use groups. The second is to associate the group with the discussion topic. This article assumes you have already created and populated the groups. If you need assistance with creating groups, please see the article titled “Creating Moodle Groups and Groupings.”
Configuring the Forum
When creating the forum, in the Common Module Settings section select Separate Groups from the Group Mode drop-down menu (as shown by the red arrow). This will ensure that only the groups you add a topic to will be able to see and respond to the topic.

Select the Save and Return to Course button to be returned to the course home page, or select the Save and Display button to go to the screen to add the discussion topic to the forum.
Adding the Discussion Topic
It is very important to select the group that you are going to post a topic to before adding the actual discussion topic. To select the group to post a topic to, click on the drop-down menu next to Separate Groups (as shown by the red arrow). After making the selection, click on the Add a New Discussion Topic button just underneath the box where the instructor’s directions for the forum appear (as shown by the red square).

Once in the Add a Discussion Topic screen, enter the title for the topic in the Subject box. Enter the text for the discussion topic in the Messages edit box. Both of these fields are required to have text, as indicated by the red text and the red asterisk (*).

Once your message is completed, scroll down to the bottom of the page. You can tell the group you are working with by the group name next to the label Group just above the Post to Forum button. When you are finished, select the Post to Forum button (as shown by the red arrow).
Please note: You will have to repeat steps 1 through 3 for each individual group you have.

You will be returned to the forum topic page. Here you will see all the topics you have posted for the group listed in the Separate Groups box (as shown by the red arrow).

You will also note that in the topic list it shows you what group the topic is associated with (as shown by the red circle). If you would like to see all of the topics you have created for every group, select All Participants from the Separate Group drop-down menu.