How to Make a Number Line for the Classroom

Integers numbers on the number line
In this example of a number line, you can see the negative numbers to the left of zero and the positive numbers to the right, all equally spaced. zizou7 / Shutterstock

A number line is a pictorial representation of real numbers. It is most commonly used in elementary math classes to help students compare numbers and perform arithmetic operations like addition, subtraction, division and multiplication.

The first mention of using number lines for understanding operations appears in John Wallis' "Treatise of Algebra." Wallis uses the visual of a person walking from point to point along a straight path to represent the image of counting from one value to the next.

Using this example of someone moving forward and backward, a number line makes the most sense represented as a horizontal sequence of whole numbers, read from left to right.

How Do You Draw a Number Line?

You can create a visual representation of number sequences using any method that makes the most sense for students comparing real number values. Real numbers include whole numbers, irrational numbers (like pi) and rational numbers (such as fractions and decimals).

However, there are some common constraints for preparing a number line. Since a number line is a small, highlighted section of an infinite line of numbers stretching forever in either direction, you should not use a shape like a square or a circle since these have defined endpoints.

Place Negative Numbers on the Left Side of Zero

Any whole number to the left side of 0 on a number line is a negative number. Negative integers are typically labeled with points or dashes.

For example, the first number on the left will be -1, then -2, and so on. These examples are important to teach students that subtracting a large number can create a negative solution.

Place Positive Numbers on the Right Side of Zero

The easiest way to show how natural numbers increase is by placing positive numbers on the right side of 0 on number lines. Beginning with zero, the right side's natural number progression is simple. If the first number is 1, the second number will be 2. This sequence will continue as long as necessary.

Space All Values Equally

Numbers on a number line are typically spaced at equal intervals. This spacing represents how each value in the figure has an equal gap between any two points, improving functionality for anyone using a number line to learn how to count or solve simple practice questions.

First, decide how many numbers you want to represent on the line and note the distance between the first number and the last value. Find your middle point and work out from the center, or measure the line and divide the length by the number of values or points to find your best interval spacing.

Does a Number Line Have to Be a Straight Line?

A number line can take nearly any form, but a straight line with dash marks to represent individual values and integers is the most simple strategy for ordering numbers.

You can choose any particular number line format that will clearly illustrate your example to students learning basic counting.

Now That's Interesting

Rolling dice can be a fun way to teach students basic arithmetic operations. You can have them subtract one roll from the next and use the number sequences to measure probability. Also, if you take a close look at a standard die, you'll find that adding any two opposite sides will always equal seven.

Original article: How to Make a Number Line for the Classroom

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