I lost a student the other day...
No not as in I didn't know where they were but that I was working through an example on the board and my method didn't make any sense to them. They pointed this out to me and I tried to explain my method in an alternative way but to no avail.
I finished the example and let the rest of the class get on with their work, at which point I went back to the example with the student. We worked through it on the board and they managed to explain where and how they got lost. Together we figured out an alternative method, which was more to their liking and I noted this down for future use.
It was nice to be able to fix someone's problems quite so easily.