What about a student who can demonstrate they can do the work in their head faster than you can work the problem on paper?

This was me in school. I was accused of cheating when we had a test. I filled in the answers and was among the first to turn mine in. I got a zero, because I didn't show my work.

The next time I got the correct answers but I still got a zero because she swore I couldn't have arrived at the correct answer that way. She publicly accused me of cheating.

I was that kid who tried to blend into the background most of the time but that upset me enough that I did something very rare for me. I started rattling off the answers to any problem she placed on the board before she could work them. Of course I was disciplined for that too, but I was beyond caring.

I've never understood why teachers get so upset when someone actually does well with the material they're teaching. I would think that would be something to be happy about but it always went the other way.