Perimeter = Distance Around OUTSIDE!

Contributor: Briana Pincherri. Lesson ID: 11303

Does your brain go around and around when you think about perimeter? You are not far off! A few videos and some polygon review, and you will be able to wrap your head around the concept of perimeters!


Measurement and Data

learning style
personality style
Lion, Otter
Grade Level
Intermediate (3-5)
Lesson Type
Quick Query

Lesson Plan - Get It!


Pretend that you have a fence around your yard (maybe you do!). Imagine a BIG BLUSTERY wind blew through and knocked the whole thing down.

  • Now the fence needs to be replaced, but how do you know how much new fence to get?

This lesson's topic will make sure you know the exact amount!

This lesson is all about the distance around the outside of a shape or, in math terms, the perimeter.

Watch this Math Antics – Perimeter video by Math Antics for a first-hand look at perimeter:

  • What is the difference between polygon and non-polygon shapes?

Now, just as the video mentioned, this lesson is only on perimeter of polygons, or shapes with straight lines for all sides. There will be no curves in this lesson, but you are sure to see them at another point in math.

  • What did you observe in the video?
  • What exactly is perimeter?

If you thought about perimeter being the distance around the outside of shapes or something about adding all of the side lengths together, you've got it! Perimeter is as simple as that.

You may see one area formula from time to time.

For rectangles, the "official" perimeter formula is P = 2L + 2W (Please note that you will get the same answer if you simply add all the sides together).

You may use whichever you prefer, but know this formula does often make an appearance on formula sheets.

Beyond that, there isn't much more to add, so let's get started with some practice.

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