ClassX Video Lessons How to Calculate Perimeter | Calculating Perimeter is easy! Learn how with real world examples.
Have you ever seen a football field? It’s shaped like a rectangle with four sides. If you walk all the way around the field and add up the length of each side, you’re figuring out the perimeter. The perimeter is simply the distance around the edge of a shape. Imagine a red line going around the field—that’s the perimeter!
Think of a fence around a yard. The total length of the fence is the perimeter of the yard. To find the perimeter of a rectangle, you add up the lengths of all four sides. For example, if a rectangle has two sides that are 7 inches long and two sides that are 3 inches long, you add them up like this:
So, the perimeter is 20 inches. The formula for finding the perimeter of a rectangle is two times the width plus two times the length.
Squares are even easier! All four sides of a square are the same length. So, to find the perimeter of a square, you just multiply the length of one side by four.
Now, let’s talk about area. The area is the space inside a shape. To find the area of a rectangle, you multiply the length by the width. Using our rectangle example with a length of 7 inches and a width of 3 inches, the area is:
For a square with sides that are 7 inches long, the area is:
Perimeter and area can be measured in different units like inches, feet, kilometers, or miles. You can find squares and rectangles with different perimeters and areas all around you!
Sometimes, you might have a shape that’s not a perfect square or rectangle. If you look closely, you might see that it’s made up of smaller rectangles or squares. To find the perimeter, measure the outside of the entire shape. To find the area, calculate the area of each smaller shape and add them together.
For example, if you have a shape made of two rectangles, you can find the area of each rectangle and then add them up. If rectangle A is 20 inches long and 4 inches wide, its area is:
If rectangle B is 7 inches long and 5 inches wide, its area is:
Add the areas of rectangles A and B to get a total area of 115 square inches.
Now you know how to find the perimeter and area of different shapes! Keep practicing, and soon you’ll see these concepts everywhere you look. Remember, there’s always more to learn about shapes and their areas, like triangles and other cool shapes. Keep exploring and have fun!
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Perimeter Walk: Go on a perimeter walk around your home or school. Choose a room or a small outdoor area. Use a measuring tape or a ruler to measure each side of the space. Write down the measurements and add them up to find the perimeter. Can you find another area with the same perimeter but a different shape?
Shape Detective: Look around your house or classroom for objects that are shaped like rectangles or squares. Measure their sides and calculate both the perimeter and the area. Try to find at least three different objects. Which object has the largest area? Which has the smallest perimeter?
Build Your Own Shape: Use building blocks or paper cutouts to create your own shapes. Make a rectangle and a square. Measure the sides and calculate the perimeter and area of each shape. Can you create a new shape by combining your rectangle and square? Measure the new shape and find its perimeter and area.
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 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. The red line going around the field represents its perimeter. Simply put, the perimeter of a shape is the distance around the edge of it. Walk along that red line, measure 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.
Now, 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. The red line around the edges represents the perimeter, and the colored-in space inside represents the area.
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 equals 20 inches.
7 plus 7 equals 14, and 3 plus 3 equals 6. Fourteen plus six equals twenty. 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 about area. Remember, the area is the space inside the rectangle. To calculate area, you simply multiply the length times the width. Using our previous example of a 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. For our square with four sides that are all 7 inches, the area is 7 times 7, or 49 square inches.
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 the units you’re using.
Squares and rectangles with 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 need 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.
For example, if the length of one side is 20 inches, you can find the length of another side by adding the other two lengths together and subtracting from the known length.
Now that we know the missing measurements, we can figure out the perimeter and area of the shape.
To find the area of rectangle A, which has a length of 20 inches and a width of 4 inches, you multiply length times width, giving you 80 square inches.
For rectangle B, with a length of 7 inches and a width of 5 inches, the area is 35 square inches. Adding the areas of rectangles A and B gives a total area of 115 square inches.
For the perimeter, you trace the outline of the entire figure and add the lengths and widths together.
To sum up, here are the steps to find the area of this irregular shape: first, find the missing measurements; then, break the figure into smaller rectangles or squares to find the overall area. For the perimeter, trace the outline of the entire figure and add up the lengths and widths.
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, check out 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.
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This version maintains the educational content while removing any informal language or unnecessary repetition.
