Undergraduate TAs

In my intro physics class, I have an undergraduate TA who is both a physics major and a future math and physics teacher. My advice to him for how he could be most helpful in class was the following:

I told him that his main job was to listen carefully to students and to scout out interesting ideas that students have. I told him that I wanted him to walk around, listen, and ask questions to see if he notices anything interesting students are talking about or using. I asked him to report back to me about interesting things he notices students are doing or thinking–it could be right or wrong ideas or procedures; it could be interesting but different solutions to problems; it could be peculiar or ordinary ideas; it could be novice or advanced ideas. I told him that it was his job to help me scout out ideas, so I that I could decide if any of those ideas needed to be elevated to the level of the entire course.

I gave him several examples of what I thought were interesting ideas that occurred over the past couple of days, which I had decided to bring to the level of the whole class. Those ideas included,

Many students not knowing where the x =0  on a x vs. t graph;

Stan’s theory about why we couldn’t see any acceleration in our data for the falling coffee filter (even though it must have accelerated at some point);

That one group got an acceleration of 6,000 mph per hour; while another group got 1.67 mph per second;

One group’s idea to “half the range” for the uncertainty in time measurements vs. the TA’s own idea about using “reaction time”;

He had already been asking students questions and helping to explain things to students. I told him that he should certainly continue doing this, but that he might ask students questions in order to find out what they are thinking, rather than to just find out if they have they right answer.

If you had an undergraduate helper in your class, what would you want them to see as their job?