# Ruler - Definition with Examples

## What is a Ruler?

Ruler Definition: A ruler is a tool used to measure lengths and draw straight lines.

Rulers are available in both **metric** and **customary** units. Most commonly used rulers in classrooms is a ruler with centimeters on one side and inches on the other.

## Reading a Ruler

Reading Centimeters: A centimeter is smaller than an inch. They are the long lines below which the numbers are written.

Reading Millimeters: A millimeter is smaller than a centimeter. The smaller lines between each centimeter line represent a millimeter mark.

10 millimeters = 1 centimeter |

Reading Inches: An inch is bigger than a centimeter. These are the larger lines on the side opposite to where centimeters and millimeters are marked.

**Measuring Objects Using Rulers **

Objects on a ruler are measured by putting one end of the object on 0 and aligning the object straight along the edges of the ruler. The mark where the other end of the object ends is the length of the object.

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