# Perimeter Background Information for Teachers, Parents and Caregivers

This page provides information to support educators and families in teaching K-3 students about perimeter. It is designed to complement the Perimeter topic page on BrainPOP Jr.

This movie will teach when perimeter is used and how to calculate it. You may wish to screen the Inches and Feet movie to review basic measurement skills. Explain to your children that the perimeter is the total distance around something. It might be easier for some children to think of the perimeter as an outline. For example, a map shows the perimeter of states and countries, and a soccer field or basketball court has lines that show the perimeter of the playing area. Come up with more examples together.

Review with your children that we find the perimeter of a shape or figure by adding the lengths of all its sides. Find the perimeter of an object together. You may want to use a pattern block or draw a shape. Find the length of each side and then add the lengths. For example, a square with 2-inch sides has a perimeter of 2 in. + 2 in. + 2 in. + 2 in. = 8 in. To help children solve these longer number sentences, you may want to review a few strategies, such as skip-counting, counting on, adding doubles, or making ten. Check out the Addition and Subtraction unit for movies on strategies. You can also encourage children to utilize a strategy mentioned in this movie, which is adding the easier numbers first, instead of adding them in the order they appear. For example, in the number sentence 3 + 2 + 5 + 3 + 7, children can add 3 + 2 = 5 and then add 5 + 5 = 10, which is a doubles fact. Then they can easily add 10 + 7 = 17 by using the adding ten strategy. Then they can count on 3 to find the sum: 17 + 3 = 20.

Practice finding the perimeter of shapes with unequal sides and shapes that have more than four sides. You may want to have children cut shapes out of paper and exchange them with other children to measure and determine the perimeter. This is a great chance to measure in inches and also in centimeters. It is also an opportunity to explore nonstandard units and practice using measurement tools such as rulers and tape measures.

Help your children understand that knowing how to calculate perimeter will be useful in many situations, especially in designing and building. Why might it be important to know the perimeter of a yard or the perimeter of a room when building a home? Discuss these purposes together.