When I have to give a big lecture with a lot of exercise groups, I have to choose the tutors who are grading the student's homework and explaining the lecture to the students.
How can I find out if someone is suitable? What are good ideas to test if someone is a good tutor without embarrassing them?
Of course, when I know the tutor or know someone who knows him, it is clear for me. Also, if someone did perform very bad in the past overall, this is a clear case. But sometimes, there are students who were very good in the given lecture but perform very bad at the exercise group (One one hand by not being good teachers, but sometimes also they cannot even solve the exercises themselves).