Hi Dale

thanks for clarifying.

The certificate is an activity so should be able to be added to a course by Turning editing on for the course and selecting Add an activity or resource.

If this isn't available then the course format may be a single activity - check under course settings and change the course format.

If this still isn't available then the activity may be hidden - Select Site admin > Plugins > Activity modules > Manage activities and Show the Certificate activity.

it isn't possible to add a certificate activity within the classroom activity as they are both activities.

Regards