AWW Board allows real time collaboration with many people. This can be used for simple answers or as a discussion tool. Maybe you want kids to read something and respond to your question. They can respond with their names attached or anonymous (for those shy students). They can also respond to each other. There is a simple free version, or you can upgrade to the paid version ($9/month). The paid version allows you to save whiteboards and much more. For an individual tutorial, contact me!
Padlet is one of the most organized and simple ways that you can get students to all collaborate on the same document at the same time (or even different times). If you've got a question you want everyone to answer, you can do it here. If you have multiple questions for them to answer, same thing. Maybe you want them to set up an outline on Padlet. You can do that too. It's a virtual corkboard full of sticky notes without all the mess of the real kind.
Flipgrid - This is a tool that anyone can use for video discussions. The teacher can set up a discussion, share the code with the students, and each student can not only respond to the teacher, but to each other as well. There is an option for the teacher to approve the videos first as well. This can be very handy for having outside-the-classroom discussions. Time limits for videos are 90 secons, but with the paid version, much longer videos are available.