Having been teaching in Thailand on and off for the last 15 years, I've seen some pretty rough acts. The worst was a lesbian Thai teacher who honestly hated males. She took this one boy, 8 years old, out to a secluded hallway, had him drop his trousers, then squeezed his nutsack until he was wailing from the pain. There were two of us shocked foreign teachers who witnessed this, and when we immediately brought it to the attention of the director, she told us dismissively to mind our own business, it was just a Thai thing.
Thailand really needs to address issues like these. There is NEVER any acceptable reason to hit a student, mild as it may seem. The lesson of "might makes right" is subhuman.