When I was at primary school there were a set of drawers which contained pieces of stationery equipment that you wouldn’t necessarily have in your own personal tidy tray. Â Round tipped scissors and pairs of compasses for drawing circles were two of the items, but the one item that you needed nearly every day was a ruler. Â The ruler drawer contained a mixture of wooden and plastic rulers, and of these I far preferred the plastic variety.
The wooden rulers were good and solid (great for slapping other kids on the back of the legs) but I always found the plastic ones easier to read and more fun once you got back to your desk. Â These rulers were normally made of clear or white plastic, though sometimes the clear plastic was tinted.
They were made by a company called HELIX, and on one end they had the words Shatterproof or Shatter Resistant printed in a font that looked like it had had a large electric current passed through it. Â They normally had metric measurements (centimetres) down one side and imperial measurements (inches) down the other edge.
Printing Shatterproof on them was of course an invitation to try and cause the thing to shatter, so these rulers went through a fair bit of punishment, being dropped from great heights, stamped on or being used as a saw on the edge of desks. Â By far the most fun thing to do with them though was to hold the ruler loosely so it hung over the edge of the desk, and then twang the end to make that funny vibrating sound. Â Even more fun could be had by twanging the ruler then sliding it back and forth on the desk to change the pitch of the vibrating sound.
However, the rulers were true to their name, and I don’t think I ever saw one shatter into dangerous long pointy shards. Â That’s not to say a fair few didn’t get snapped in half, but when they did break they broke cleanly and so would never become the playground equivalent of a broken bottle in a pub fight.