Google has enabled some new features in Meet that address some of the common frustrations that teachers experience!
Mute All: In the Participants panel, there is now a Mute All button which does just what it says - it mutes all attendees in the meeting. It does not prevent attendees from unmuting themselves again, but it's a useful tool to quiet the class if you need to get a word in.
End Meeting for Everyone: This is one of the most requested tools teachers have requested - the ability to close the meeting and eject all attendees. This is super useful to ensure students don't hang around and socialize after the teacher has left, and it also prevents "orphaned meetings" hanging around that students find later and use as hangout rooms. When the meeting organizer clicks the hangup button they now have two choices: Just Leave (which leaves the meeting running for the remaining atendees) or End the Call (which ejects everyone and closes the meeting).