When my husband was in first grade, his mom noticed that his arms were covered with tiny violet half-moons. So were his friends' arms. Turns out that this vicious teacher was digging her nails into them when they missed questions. The school told my in-laws that they couldn't fire her until the end of the year.
Back in the day, you didn't have much recourse when that stuff happened.
The evil old witch must be 90 and still lives around the corner from my in-laws.