When in an active learning classroom your role is that of a facilitator. Instead of providing students with all the answers, it is your job to give them the background and advice that they need to come up with answers on their own. Therefore, unless you are answering routine questions of procedure or clarification, you will likely want to answer student questions with guiding questions that help them think through the issues surrounding their own questions. Otherwise, if students know that you will give them the answers, then they will come to learn to rely on you as a source of answers instead of learning how to generate answers themselves.
To monitor student progress on an activity and to help struggling students, you want to be sure to wander around the room while students are working. Listening in on conversations, adding comments, questioning students on their progress and how they are thinking about the task will be helpful for both you and the students. You can see where students are having difficulty and give points of clarification to the whole class if necessary. You can also use the information you’ve gathered in walking around the room in deciding which groups to call on if you decide to bring the class back together at the end to talk through potential answers (see planning in-class activities).
Finally, if you are working with TAs to help run the in-class activities, you want to make sure that they understand their role as a facilitator as well and be clear with them about what kinds of questions they should answer directly, what types of difficulties should be brought to your attention, and give them suggestions on how to guide students to answers instead of giving them the answers. CTL offers a semester-long TA Training for this type of teaching. For more information, see our SAIL program page.