One of the most amazing successes of Qin Shi Huang, who built the Great Wall of China, is the standardization of weights and measures for length, mass, and weight. Did you know that people in the past used different ways to measure things like length, weight, and mass? Let's talk about length, for example.
In Eastern cultures, they used a unit called "ja" or "cheok." It's the length from the tip of your thumb to the tip of your middle finger when your hand is open. In the past, it varied between 18 centimeters and 24.5 centimeters.
In Korea, they also used this unit, but it changed a few times. In the U.S. and U.K., they use a unit called the "yard" for length. Imagine the distance from your nose to your fingertip—that's about one yard! In the past, the yard used to be different in the U.S. and U.K., but now it's the same length everywhere.
