Calculating Perimeter
📚 What You'll Learn
- The difference between perimeter (distance around) and area (space inside)
- Using a ruler or grid lines to measure each side
- How opposite sides of a rectangle are equal
- Adding all side lengths to find total perimeter
In this video, we're going to be calculating the perimeter of a rectangle.
What does perimeter mean? Well, it's a measurement. Like area measures the space inside of a shape, perimeter measures the distance around a shape. To measure distance, we can use a prism ruler. You'll notice that each of the lines on the grid are also one prism unit apart. So you can use those to measure as well.
Let's either use the grid lines or our prism ruler to find the perimeter of this rectangle. The length of this rectangle is nine prism units. And the cool thing about rectangles is that opposite sides are equal so I don't even need to measure this side. It is also nine prism units.
And now let's measure the width. This time, I'm going to measure using the grid. From here to here is a distance of one prism unit, two, three, four prism units. And that means the opposite side of this rectangle will also be four prism units.
Now we're ready to calculate the perimeter. Let's add up all of these distances around the rectangle and find the total. Nine plus four plus nine plus four equals twenty six prism units. That's the perimeter of this rectangle.
And now you're ready to calculate the perimeters of different rectangles on your own.