Create a course C1 with separated courses Create two users, t1 and s1. Enrol t1 in C1 as a non editor teacher and enrol s1 in C1 as a student. Change permissions on non editor teacher and prohibit moodle/site:accessallgroups (applies too to teacher if you change it)  Create 2 groups.  Assign t2 to group 1 and Student to group2 Create a Forum with "whole forum grading" Login as s1 and add a Post on forum Login as t1 and click on grade  The user list show 2 users and error when you try to navigate to Student (because don't belong to your course)  The user list don't check if you can assess to this student