### New prefixes for the metric system

**Directions for teachers:** Ask students to read the online Science News article “The metric system is growing. Here’s what you need to know,” which explores new prefixes for the metric system. A version of the article, “The metric system gains new prefixes,” appears in the January 14, 2023 issue of *Science News*.

**1. What are the new metric system prefixes? How are they represented numerically compared with a base unit of measure, for example one meter?**

The new metric system prefixes are ronna-, quetta-, ronto- and quecto-. One ronnameter is 1 x 10^{27 }meters, and one quettameter is 1 x 10^{30 }meters. One rontometer is 1 x 10^{-27 }meters, and one quectometer is 1 x 10^{-30 }meters.

**2. When and where were the new prefixes adopted?**

The new prefixes were adopted November 18 at the 27th General Conference on Weights and Measures in Versailles, France.

**3. What was one sign that new prefixes were needed, according to Richard Brown?**

People started coming up with their own prefixes, such as “bronto-.”

**4. What is the global system of measurement called? Why is it beneficial for scientists to use a shared system and set of prefixes? Explain.**

The International System of Units is the world’s most widely used system of measurement. If scientists agree on units and prefixes, they can communicate and understand each other with less room for confusion.

**5. What are the masses of Earth and an electron using the new prefixes? Why might these prefixes be beneficial in some cases?**

The mass of Earth is six ronnagrams. The mass of an electron is about one rontogram. In some cases, smaller numerical values might be easier to understand and compare.