TodaysMeet has changed a bit as users can now create accounts and close chat rooms as they wish. There are also some paid features for teacher control that I haven't perused. It would be handy to have more control. If you are just looking for a free option, stick with a regular account.
Back-Channel discussions are a great way for teachers to glean information from the audience. Students can pose and answer questions in a quick format as they are limited to 140 characters. If you aren't confident in the trustworthiness of your entire class, test it out with a group of students during one of your lessons. Pull up the discussion afterward for the class to view. That may just provide the hook for the rest of your class to be ready to jump into TodaysMeet.
My last tip is to come up with some guidelines or rules. I would suggest that you discuss it with your class as to what they think guidelines should be so that they feel a part of the decision making process. Here are a few ideas to consider though:
- If it isn't important, don't say it
- Type in complete sentences
- Reread before you submit
- Reply to others with @ and their name (@fred)
Update: Matt Miller (Ditch that Textbook) did a fantastic job of coming up with a list of ways TodaysMeet could be used. I highly recommend you peruse his thoughts on the subject. http://ditchthattextbook.com/2014/01/30/20-useful-ways-to-use-todaysmeet-in-schools/