Have you ever seen a football field? It’s shaped like a rectangle and has four sides. If you walk all the way around it, adding up the length of each side, you’re figuring out something called the perimeter.
The perimeter is the distance around the edge of a shape. Imagine a fence around a yard; the total length of the fence is the perimeter. So, if you walk along the edge of a shape and measure how far you’ve gone, that’s the perimeter!
Now, let’s talk about area. The area is the total space inside a shape. So, while the perimeter is the distance around the outside, the area is all the space inside.
Let’s say we have a rectangle. If the length of the rectangle is 7 inches and the width is 3 inches, how do we find the perimeter? We add up all the sides: two sides of 7 inches and two sides of 3 inches. That gives us a perimeter of 20 inches.
For a rectangle, the formula for the perimeter is two times the width plus two times the length. If you have a square, it’s even easier! Since all sides are the same, you just multiply the length of one side by four.
Now, for the area, you multiply the length by the width. So, for our rectangle with a length of 7 inches and a width of 3 inches, the area is 21 square inches (because 7 times 3 equals 21).
If you have a square with sides of 7 inches, the area is 7 times 7, which equals 49 square inches.
Remember, you can measure perimeter and area in inches, feet, kilometers, or miles, depending on what you’re using.
Shapes with different perimeters and areas are everywhere! But what if you have a shape that’s not a rectangle or a square? Sometimes, you can break it down into smaller rectangles or squares to find the perimeter and area.
For example, if you have a shape made of two rectangles and a square, you can find the perimeter by measuring the outside of the whole shape. To find the area, find the area of each smaller shape and add them together.
Sometimes, you might need to find missing measurements. For example, if one side is missing, you can use the lengths of other sides to figure it out. Look at the lines directly across from the missing side for clues.
Let’s say we have a rectangle A with a length of 20 inches and a width of 4 inches. Its area is 80 square inches (because 20 times 4 equals 80). Rectangle B has a length of 7 inches and a width of 5 inches, so its area is 35 square inches.
Add them together, and the total area is 115 square inches. To find the perimeter, trace the outline of the whole shape and add up all the sides. In this example, the perimeter is 62 inches.
So, to find the area of an irregular shape, find any missing measurements, break the shape into smaller parts, find the area of each part, and add them together. For the perimeter, trace the outline and add up the lengths and widths.
Think of it like a puzzle! Once you start noticing shapes around you, you’ll see perimeter and area everywhere. Keep exploring and learning!
Shape Hunt: Go on a shape hunt around your home or school. Find different objects like books, tables, or picture frames. Use a ruler or measuring tape to measure the length and width of these objects. Calculate the perimeter and area of each object. Can you find an object with the largest area or the longest perimeter?
Perimeter and Area Art: Create a piece of art using paper shapes. Cut out rectangles and squares of different sizes. Arrange them to form a picture or pattern. Calculate the perimeter and area of each shape you use. Add up the total area of all the shapes in your artwork. Share your creation with your class and explain how you calculated the perimeter and area.
Design Your Own Park: Imagine you are designing a park. Draw a layout of your park using rectangles and squares for different areas like a playground, garden, or pond. Decide the length and width of each area and calculate the perimeter and area. Think about how much space each part of your park will take up. Present your park design to your family or friends and explain your calculations.
Sure! Here’s a sanitized version of the transcript:
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Calculating area and perimeter for kids.
As you know, a football field is shaped like a rectangle and it has four sides. If you walk along the edge of that rectangle all the way around and total up the length of each side you walk, you would be figuring out the perimeter.
Simply put, the perimeter of a shape is the distance around the edge of it. Walk along that line measuring how far you’ve gone, and you’ll have the perimeter. Another way to think about it is to picture a fence around a yard; the total length of that fence is the perimeter of the yard.
And what about the area? The area is the total space inside the yard. So, the perimeter is the distance outside of a shape, and the area is the space inside of it.
Let’s assume the length of both sides of this rectangle is 7 inches and the width of both sides is 3 inches. To find the perimeter, we add up the two sides of 7 inches and the two sides of 3 inches, which would equal 20 inches.
The straightforward formula for finding the perimeter of a rectangle is to take two times the width and add it to two times the length. But what if you have a square? That’s even easier! Since all four sides of a square are the same length, the perimeter of this square yard would be the length times four.
Now that you know about perimeter, let’s talk area. Remember, the area is the space inside the rectangle. All you have to do to calculate area is multiply the length times the width. Using our above examples, for a rectangle that has a length of 7 inches and a width of 3 inches, the area is 21 square inches because 7 times 3 equals 21.
For a square that has four sides that are all 7 inches, the area is 7 times 7 or 49 square inches. Makes sense? Perimeter and area are pretty easy once you learn the formulas.
It’s important to remember that the measurements of perimeter and area can be in inches, feet, kilometers, or miles, depending on whatever units you’re using.
Squares and rectangles with all different perimeters and areas are all around us. But what if you don’t have a square or a rectangle? What if you’re trying to find the perimeter and area of an oddly shaped space?
If you look closely, you’ll see that there are actually two rectangles and one square that make up the shape. To find the perimeter of this shape, you just have to measure the outside of the entire shape.
To find the area of the shape, you have to find the area of each of the smaller figures and then add them together. Sometimes finding the measurements of an odd-shaped figure can be tricky when you have limited information.
Notice that there are missing lengths. The length of the green line is 20 inches. This will help you find the length of C. First, we add the other two lengths together: 6 inches and 9 inches to get 15 inches. Then we subtract 15 from 20 to get 5, so the length of line C is 5 inches.
Next, to find the width of lines A and B, take a look at the width of the lines directly across the figure for help. The key to finding missing measurements of odd-shaped figures is to observe the lengths or widths directly across from the missing measurements.
Now that we know the missing measurements, we can figure out the perimeter and area of the shape. Let’s start with the area. We know the length of rectangle A is 20 inches and its width is 4 inches. Since area equals length times width, the area of rectangle A is 80 square inches.
We know that the length of rectangle B is 7 inches and its width is 5 inches. Since the area is length times width, its area is 35 square inches. Now, if we add together rectangle A and rectangle B, the total area is 80 plus 35 or 115 square inches.
But what about the perimeter? We need to measure the outside of the figure. Watch as we trace the outline of the entire figure and add the lengths and widths together as we go.
So, our perimeter is 62 inches.
To sum up, here are the steps to find the area of this irregular shape: first, find the missing measurements; then cut the figure into smaller rectangles or squares to find the overall area; find the area of each smaller figure and then add them together.
To find the perimeter, trace the outline of the entire figure and add up the lengths and widths. If it helps, you can think of the odd shape as a puzzle that you are taking apart to discover the area, then putting it back together again to find the perimeter.
Now you know the general idea of perimeter and area. Of course, there’s a lot more to learn. For more about area and how it applies to shapes like triangles, trapezoids, rhombuses, and others, watch our other video about area.
In the meantime, think about perimeter and area as you see squares and rectangles all around you. Once you start, you won’t be able to stop noticing lengths, widths, and spaces in between.
Hope you had fun learning with us! Visit us at learnbrite.org for thousands of free resources and solutions for teachers and homeschoolers.
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