Just rolling out is this under reported feature. Until today, if you wanted to set a students the attendee role in a Teams meeting you would either have to do it before the start of the meeting, or manually during the lesson.
With this new option, accessible from the participants window during a meeting, you can now change the students to attendee during the lesson.
Then change the Who can present option to Only me, and you’re all set.
It’s a really simple but elegant solution to an ongoing issue for teachers. I’m surprised this hasn’t been promoted more by Microsoft.