If you have been looking for an alternative to TodaysMeet and haven't found one you like, give Yo Teach! a try. The option to have students draw on a whiteboard and insert those drawings into a chat is simply fantastic. In a math class you could have students show their work or highlight a portion of a problem on which they need help. You can also insert a drawing to aid an explanation.
YO Teach is a very user-friendly tool to use to create a backchannel chat by simply creating a room and then setting a password. Students can then join via a URL, and the admin feature allows educators to set privacy settings and moderate users. Finally, students are even able to draw on a “scratchboard" and have that show up in the backchannel.