Rulers are used to measure lengths and distances.

Here are some important facts about rulers:

• They are sometimes referred to as rules or line gauges.
• The two most common scales used on rules are metres (metric) and inches (imperial).
• Rulers come in different styles and lengths. Common lengths are 15cm, 30cm, 50cm and meter rules.

Here are some examples of rulers:

One thing to note with rulers is that the zero of the ruler is not always at the end of the ruler.

You need to check this on each ruler you use:

Rulers are often used to help line things up as a straight edge, as well as using them for taking measurements of length.

This makes them a highly versatile piece of apparatus.

Here is an example of a ruler being used to line up other measuring tools to find the width of the mass: