Which unit would probably be most appropriate for measuring the length of an insect?

• A. Centimeters
• B. Millimeters
• C. Kilometers
• D. Meters

Answer: (B)

When you’re measuring something very small, you choose a unit that keeps the number you write at a practical size and easy to read. Insects are usually a few millimeters long, sometimes up to a couple of centimeters, so using millimeters gives a precise, straightforward measurement like 5 mm or 12 mm. Using kilometers would be far too large, and meters are usually too coarse for tiny lengths; centimeters can work for larger insects but don’t cover the small end as well. Millimeters hit the right balance for describing most insect sizes, making it the best choice.