In groups, we derived the equation for the electric field around a point charge. It wasn't that bad, and it let us have some really great discussion about what the variable q means in different situations. What makes q₁ different that q₂, q, and Q? It was a good discussion about what variables mean.
We also got really good at drawing the direction of electric field lines. I couldn't even think of any good questions to ask them.
When we were reviewing for the exam, I spent a lot of time talking about conscious competence. We will go through the steps, we'll know the steps are right, and yet, still, at the end, we're sure we made a mistake. It's not uncommon. We all have our physical intuition be at odds with the models of physics all the time. But it's a new feeling for first-year physics students, so I spent some time explaining how it's normal. It's worth doing what you know is right, even if it isn't exactly what the question asks, than sit there and do nothing. Get involved with the problem. Figure out the situation really is. The more you think about a situation, the easier any question about that situation is.
I also got a very clear reminder that students don't learn at the same pace when a student asked me how to read numbers aloud that are bigger than nine thousand nine-hundred and ninety-nine. I drew this picture, and he got it almost instantly: