NetViewer Meet is an online conference and screen sharing tool. It consists of two downloads: a Moderator and a Participant app.
As a moderator, you can:
- Control which screen to be shared, yours or a participant's
- Control who receives remote control over the displayed screen
- Select whose video signal to be transferred. You could transfer your own video, and grant rights for others to transfer theirs
- Control who is allowed to transfer their speech into the meeting
- Control session recording
These features should allow you to hold a lecture and a question/answer session afterwards simply by activating the asker's screen and voice/video signals. You could also appoint a participant as a co-moderator (in case you have a TA)
The participants are able to:
- View the screen and video selected by the moderator
- Use their pointers to point at items on the screen
- Share their voice, video, or screen (only after the moderator grants them the right to do so)
These features would allow the students to watch the lecture, and then participate in the question/answer session by sharing their own screen afterwards
Note that there has been an option to upgrage to GoToMeeting ever since NetViewer was acquired by Citrix, but I have not used that upgrade, so I can't give a definite recommendation