Ruler

measurement · geometry · tools

Ancient invention. People have been using rulers for over 4,600 years, since at least 2650 BC, making them one of the oldest tools humans created.

Marked with numbers. Rulers have a series of small lines called "rules" or markings along the edge that show you exactly how long something is, usually in inches or centimeters.

Double duty tool. A ruler does two jobs at once: it measures things AND it helps you draw perfectly straight lines because its edge is completely flat and even.

School essential. Rulers are super important in geometry, geography, and math classes because they help students measure accurately and create precise drawings.

Many types exist. You can find rulers in different lengths and materials, from wooden ones to plastic ones to metal measuring sticks, depending on what job you need to do.