Welcome to Moodle! The docs are a good place to start (Groups) (Groupings) to learn about different features.
One thing I will say is that I thought I had eliminated all trace of kids knowing about groups, but then I realized they could see what groups they were in in their profiles, so I had to remove groups from appearing there (in Admin - Users - Permissions - User Policies: scroll down to Hide user fields, and in addition to what you have already selected there, select 'Groups'
Hi,
Not sure if you have resolved this but go to your course.
In Course Administration -> Edit Settings
Go down to the Groups section and change to Visible Groups. This will mean the students know nothing about the groups.
HTH
Hello! Unfortunately, I could not solve the problem because none of the above mentioned options appear in my version of Moodle. But I found out that the students cannot see the groups anyway. I switched roles to see the course as a student and also I checked with my students and they told me that they cannot see the groups. I believe it all depends on the your Moodle settings and whether you can change the settings or not.
If it helps, you can see the version of Moodle in use if you click at the bottom of the page on Moodle Docs. At the top of that page it will show the version.