A ruler is a very useful instrument used to measure distances or to draw a straight line. There are different types of rulers used in different areas of our personal daily life. They can be made of wood, plastic or even metal. Most common rulers are desk rulers and are used for measurement, drawing straight lines and as a guide for cutting.

Most common desk rulers have two edges. One of them allows to measure distances using the metric system, while with the other edge, we can obtain measurement results using the English system. Desk rulers are usually one foot (or 12 inches) or 30 cm long.

Metric rulers are very easy to read. They deal only with centimeters and millimeters. The metric ruler has three main lines. The larger ones with numbers are centimeters, the middle ones indicate half of centimeter (5 millimeters) and the smallest lines represent millimeters. A millimeter is 1/10^th of a centimeter.

Measuring with Metric rulers

Now, with a pen make two points on the piece of paper and place one end of the ruler at the first point and move the ruler’s other end until it touches the second point. Look at the number on the ruler. If the point is between two numbers, for example 8 and 9, mark the lower one. Now look at the millimeters lines between those two numbers and count them. If the point lies, for example, on the fourth line, it means there are four millimeters between the point and the centimeter number. To get an exact distance between two points, combine the centimeter and millimeter number together. In this case, the distance is 8.4 cm.

English rulers are more difficult to read, mostly because they deal with fractions. An inch is divided into 8 or 16 equal parts. Some rulers have inches divided even into 32 or 64 equal parts. Most common desk rulers are divided into 8 parts and have 3 different lines. The longest one in the middle is half inch (1/2), then the next shortest line is one quarter of inch (1/4) and the smallest line represents one eight of an inch (1/8).

Measuring with English rulers

As above, measure the same points but this time using an English ruler. If the point lies between two numbers, 3 and 4, mark the lower one. Count the smaller lines between the big numbers. The point should land on 3^rd line which represents 3 eighths of an inch. To get the complete number, combine those two partial ones. Mark the whole inch, followed by a space, then the fraction of an inch. In our case total distance is 3 3/8 inches.

Reading a ruler is a very useful skill that you will likely use whenever you need in your job, while doing household work or any hobby.