Metre

High school (ages 12+)
Mathematics & Numbers

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/metre

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. How long is Metre?The fundamental unit of length within the International System of Units (SI)
2. What is the historical definition basis?Initially defined as one ten-millionth of the Earth's polar circumference (1791)
3. How was the metre originally defined?In 1791, the metre was set as one ten‑millionth of the distance from the equator to the North Pole along a meridian. This linked the unit to the size of the Earth.
4. Why did scientists change the metre’s definition to use light?The metre was changed to be based on the distance light travels in a vacuum during 1/299,792,458 of a second. Light’s speed is the same everywhere, so the metre becomes more precise and stable.

International System of Units (SI): The globally adopted modern metric system, comprising seven base units defined by fundamental physical constants.
Geodesy: The scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a time-varying three-dimensional space.
Physical Constant: A physical quantity that has a numerical value and is constant in nature, serving as a fundamental basis for scientific definitions.
Metrology: The scientific study of measurement, including its theory, practice, and application.