Description: The Strong Roots That Have Supported the Development of Science — The Power of Unified Standards When people wake up in the morning, they check the clock to see what time it is. At the market, they buy 600 grams of meat, and at the hospital, they measure height, weight, and eyesight. We can do all of these things as a matter of course because we have a common set of criteria — 'standards.' A standard is a fixed criterion used to measure things like time, weight, and length, set to be the same everywhere in the world. Establishing unified standards has been considered important since ancient times. In order to build a fully unified nation, Qin Shi Huang of China first unified the standards for measuring length, volume, and weight. Because countries that had used different units were now combined, there were great difficulties in everything that required measurement — collecting taxes, measuring land area, and recording the amount of goods produced. In Korea as well, units such as *cheok*, *seok*, and *geun* are recorded in historical texts like the *Samguk Yusa* and *Samguk Sagi*, and it is said that the measurement system of Unified Silla continued through the Goryeo and Joseon dynasties, being used in agriculture, commerce, and many other fields. Of course, standards remain hugely important today. In particular, fields where numbers and measurements matter greatly — such as the space industry, cutting-edge technology, and future industries — must rely on precise standards, since even a small error can cause a major problem. In addition, when parts made in different countries are combined to complete a single product, or when goods are traded between nations, unified standards are used as the basis for determining the quantity and size of products. In [Why? Standard Science], children can learn how standards used in these various fields are determined, and what kinds of standards exist all around us. Reading this book will help children understand the importance of standards and build a broad, solid foundation of knowledge. 1. To the Korea Research Institute of Standards and Science — 8 2. The Prototype for an Unchanging Standard — 15 3. A Time Trip to Ancient City-States — 21 4. Why Standards Matter — 29 5. The Beginning of Weights and Measures — 36 6. Units That Began with the Human Body — 43 7. Rooting Out Corruption — 50 8. Weights and Measures for All Eras and People — 60 9. The Birth of the Meter — 69 10. The Creation of the Metric System — 74 11. The One and Only Prototype in the World — 83 12. Why Time Is Divided So Precisely — 88 13. Accused of Betrayal — 96 14. The Ampere, the Unit of Electric Current — 103 15. The Kelvin, the Unit of Temperature — 111 16. The Candela, the Unit of Luminous Intensity — 117 17. The Unit of Amount of Substance and Scientific Notation — 123 18. Companions in Crisis — 131 19. Derived Units Made from Base Units — 135 20. Unifying the Kingdom — 141 21. Units, the Universal Language — 146 22. The Future of Measurement Standards — 152 23. Returning to the Present — 157