Rulers

A ruler is a simple tool that helps people measure things. It is usually a flat strip of wood, plastic, or metal. Rulers have marks along the edge to show inches or centimeters. Kids use rulers in school for math and art projects.

History of the Ruler

Rulers have been used for thousands of years. The oldest known rulers came from an ancient place called the Indus Valley. They were made of ivory and were very accurate. Long ago, people measured things using their hands or feet. Rulers made measuring much more exact and easier to share.

How Rulers Work

Most rulers are 12 inches or 30 centimeters long. One side shows inches, and the other often shows centimeters. You line up the zero mark with the start of what you want to measure. Then you read the number at the other end. Rulers also help you draw perfectly straight lines.

Fun Facts

• The word 'ruler' also means a person who rules a country.
• Some old rulers were made from gold or silver.
• A yardstick is a long ruler that is 36 inches long.

Did You Know?

The oldest ruler ever found is over 4,000 years old and still very accurate.