Understanding Shapes: Finding the Perimeter and the Missing Length

Learning to find the perimeter of a square is the foundation to advancing to other shapes and calculations. Since all four sides of a square equal one another, it should be easy to teach your kids how to find the perimeter of a square.

Perimeter of a square is the distance around the exterior edges of the square. That means, adding all the sides up or multiply the length of a side by 4. For example, if you are given 1 side of a square, in this case, 2 cm, the perimeter of the square is simply 2 x 4, which equals 8. Therefore, the perimeter of this square is 8cm. To challenge your kids further, ask them to find the missing length of a shape. We can use a rectangle to demonstrate the steps. In this concept, you are given the perimeter of the rectangle, which is 24 cm. You know that one side of the rectangle equals to 6 cm. To calculate the missing side of a rectangle, you will need to get your kid to first learn the formula:

2 (Length + Width) = Perimeter of a Rectangle

With this in mind, you simply need to input the numbers in the equation to solve for the missing side:

2 (6 + x) = 16
6 + x = 8
x = 8 – 6 = 2

Therefore, by using simple algebraic expression, you can easily find that the missing side in this example is 2 cm.

Overall, the perimeter is closely related to how many known and unknown sides you have in a shape. This theory is applicable to all the regular shapes, except for circles, which uses circumference instead of perimeter to calculate the measurement of its exterior sides. 