Breakout Rooms - Can the host join one of the Rooms?

So as host of the meeting, you can't assign yourself to a breakout room, but you can join any of them once they're opened.

I would create your rooms and have the students move to the assigned breakout room.  You'll be in the main meeting room by yourself then when this happens.  From there in the Breakout Rooms menu that lists the rooms and who is in them, you would click the blue "Join" button for the room you want to enter to work with your student. 

Hope this helps.  If so please click the Accept as Solution button.

KJH