Hi, Rob
Okay. Sure, that's definitely possible.
First I would advise checking out the docs - http://docs.moodle.org/25/en/Roles_and_permissions for more information on roles and permissions.
By default, the Learner Role is able to view Participants in a Course. There are a couple of ways you can disable the ability for the Learner role to view Participants. This would be dependent on your requirements of course.
1. Disable the ability to view Participants at system level. This removes the ability for Learners to view Participants completely.
- Site Administration > Users > Permissions > Define Roles
- Edit the copied Learner role (see below) and disable View Participants under Course
Important note: If you are going to make tweaks to role definitions, make a copy of the role you want to modify and tweak that one. That way, if you mess anything up, you can revert back to the Learner role without any hassle. You can then assign your copied Learner role as the role for Learners under Site Administration > Users > Permissions > User Policies
2. Disable the ability to view Participants at course level. This allows granular control for specific courses, rather than across the whole system.
Course Administration > Users > Permissions
- Select the Learner role from the drop-down as the role to override
- Set View Participants under Course to Prevent
If you think that you need View Participants disabled for the majority of course, I would advise point 1. You can then allow visibility of Course Participants by following step 2 and choosing Allow instead, for those courses you want to allow visibility of Participants for.
Cheers
Tom