Tom Richey that he was going live with a review session for AP European History students. When I joined in there were nearly 2,400 viewers and at one point there were over 2,500 viewers. Tom was talking to students in his own classroom and broadcasting the review for anyone who wanted to watch. A bunch of classrooms around the U.S. were watching.
What Tom was doing is something that many other teachers could do for a small or large audience. If you're hosting a review session for students during school hours or after school hours, streaming it on YouTube Live will let the students that can't be in the room with you, follow along and ask questions too.
Broadcasting on YouTube can be done from your Android phone or iPhone. You can also broadcast from your laptop, but the set-up is a little more difficult than it is on a phone. Here are the directions for broadcasting YouTube Live from your laptop.