How to know who has dismiss an user

Hi

We are using jitsi to teach a children class, but frequently some of the children dismiss other classmates or even the teacher.
How can we know who has dismiss another users and how can we avoid it?
Thank you

I take it that you are referring to meet.jit.si, you may consider using moderated jitsi for your classes, the link is just below the meeting name box on the welcome page.