Razor blades for school children
I remembered this by accident, and after relating it to my team members at work, I realized how interesting it is. Back in Romania, I had just started first grade, and the teacher was telling us what types of supplies we should bring. She told us to bring razor blades, specifically the ones with two edges, not the fancy multi-blade modern razor blades.

The idea was to encourage children to write properly. The emphasis was on cursive (we even had to take a calligraphy class in second grade), and if I think about it, we were never taught to write anything but cursive. To reduce the number of mistakes children make when writing, they were (almost) forced to only use styluses and write in ink because it was much more difficult to erase.

Back then, white-out hadn't yet arrived in Romania, and the only erasers you could find were only of the crappy, soft kind, and didn't have the sandpaper-like end which could be used to erase ink. So then someone realized that razor blades could be used to scrape a thin layer of paper, effectively erasing the ink.

So school children were encouraged to bring razor blades to class. While it sounds amazingly unsafe, you have to remember that this was in a society where seven year old kids were trusted to go home by themselves after school, and often operate gas stoves to warm up their meals, way before the parents came home from work.