I don't remember when I first used a ruler or measuring tape. Chances are good that I used rulers for their straight edges before I ever understood what all those little markings were about. I remember having a little geometry kit in grade school, when we started learning about triangles. I remember how everyone used the protractor to scratch their desks. It may have been the first sharp point we had access to, in those days of safety scissors. I don't remember particularly liking geometry when I was in school. It may have been one of the units I was better at, but I was never really amazing at math. And I certainly didn't love measurement back then.
The first time measurement really became an issue was when I learned how to draft. I took a design technology class in my last year of high school, which wasn't an unmitigated success. I was in my very truculent phase, because I hadn't yet learned how to be strategically pleasant. My teacher and I didn't have a particularly good relationship. But there were scale rulers. Scale rulers are fascinating, because they don't have a 1:1 relationship to the world. Those strange, triangular rulers, with two different scales on each side, are six different representations of miniature worlds. I can't remember what the ones in high school were like, whether they were metric or imperial, what scales they had. The one I bought when I started design school, though, was metric. It had 1:20, 1:25, 1:50, 1:75, 1:100, and 1:125. At some point, I used the 1:125 side to mark a line with a black marker. There's still a long scuff between the 2 metre mark and the 18 metre mark. Which is what's fascinating about scale rulers. The ruler itself is the length of my forearm and half of my hand. But the markings tell a different story. That 1:125 side goes up to 37.5 metres. On the smallest side, the 1:20, it goes up to 6 metres. A scale ruler tells a story about a tiny world, drawn on paper. It's hard not to start noticing measurement when your ruler suddenly shows you something other than the immediate world you live in.
In design school, I finally understood the value of cartesian space. In math class, back in grade school and high school, it took mnemonics to remember which axis was X and which was Y. All I ever used those for at the time was making graphs. Having a convention for length and height was no use to me until I started designing objects.
It took me a master's degree to develop a love of standards, which was the precursor to a love of measurement. Developing an understanding of the global infrastructure required to bring a cup of tea or a piece of toast to the kitchen table was a revelation. Metrology, the science of measurement, is one of the extremes of standardization. Just think: in order to buy a cheap plastic ruler today, eighteenth century scientists had to make expeditions around the world, determining the circumference of the Earth by measuring the lengths of degrees at different locales; international fights had to be fought over whose system of measurement would be adopted by scientific institutions; physical representations of standard measurements had to be distributed to regional governments and standards bodies; entire populations of people needed to learn to think in decimals. The way we see the world had to be changed in order for the ruler we now take for granted to both be developed and to become understandable. It's one of the triumphs of early modern rationalism. It's completely audacious. And we take it so much for granted.
That history, and the systems supporting our current standards, is embedded in every interaction we have with measurement. That ruler, which may seem so obvious, because all it does is tell us how long something is, is a spectacular attempt to make sense of our world. To hold a ruler up against an object and say "this is 20 cm long" is entirely commonplace now, but is a spectacular achievement, and a spectacular arrogance.