How bad was that teacher? Reminds me of a supervisor I had at my first job. He was showing me how to run a ceramic deburring tumbler cutter (it had several cutting wires activated by an electric eye) and instructed me to NEVER put my hand in front of the cutters. Not 15minutes later I had an issue with the machine, he came over to check on it and promptly put his hand down right in front of the cutter head. Several parallel cuts and a lot of bleeding later, I understood why one should not do that…
Are those the gospel singing Gaithers?