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Lesson 3: Introducing Perimeter

Brain Teaser!

Let’s get our brains warmed up! Complete the challenge below, what did objects did you find around your home that measures 15cm long?


Today we are going to learn how to measure the perimeter of a 2D shape. What is perimeter? How can we measure the perimeter of a 2D shape? Discuss these questions with a grown –up at home.

Once you have done this, work through the PowerPoint below on Perimeter to give you a deeper understanding of the topic. Look at the examples and try to work out the answers.

Watch the YouTube clip below demonstrating how to calculate the perimeter of 2D shapes.

Calculating the perimeter

Work out the perimeter of these 2D shapes.


Now that you’re confident to measure the perimeter of 2D shapes, we would like you to walk around your home and find at least 5 objects or more to measure using informal methods.


We would like you to complete this table smiley



Length of object using informal units



e.g. door frame



6 + 12 + 6 + 12 + = 36 hand spans