How to calculate perimeters. For 5th grade math.

NGSS Science Videos

This video helps children prepare for state math exams by explaining how to solve a retired (released) question from an actual state exam.    - If you want to copy any of our more than 100 free Google Forms (all with questions and links to free-access educational videos we've made), then please download this free file from TPT and it will give you directions for how to access them: https://www.teacherspayteachers.com/Product/State-Math-Test-questions-and-answers-as-a-Google-Form-2022-Q6-10-V2-11530867   Other free resources we've made:  - For links to many free educational resources, please visit our website (no 3rd party advertising, no subscriptions, no paywalls): https://TestPrepLLC.org/   - For our free apps for Apple's Mac and iPad (collects no data, no advertising, no subscriptions, no paywalls, no in-app purchases), please visit our page on the Apple App Store. These apps include Common Core and State based practice tests in math, and State science exams based on NGSS and State curriculums (all with detailed, colorful explanations): https://apps.apple.com/us/developer/test-prep-llc/id1727786893   Best wishes,  The staff at Test Prep LLC  https://TestPrepLLC.org

Transcript

00:00Please see the link in the description to download a worksheet for this video.

00:05One of the rules for playing soccer is to keep the ball inside the edge of the soccer field.

00:10A soccer field is surrounded by a white line that looks like a giant rectangle.

00:14Likewise, a giant rectangle surrounds this basketball court and defines the edge of the

00:19court. The players have to keep the ball inside this area. Here are some tennis courts which

00:25also have a line that defines their boundaries. In math, we call the distance of this

00:29boundary the court or field's perimeter. We can calculate this distance by adding up the

00:34distance of this side to the distance of this side to the distance of this side and to the

00:39distance of this side. For a tennis court, this value is 228 feet. In this video, we'll learn

00:46what a perimeter is, how to calculate the perimeter of a rectangle, how to calculate the perimeter of

00:52a triangle, and how to calculate the perimeter of a shape that doesn't have a name.

00:57Let's start by talking about what a perimeter is. In math, a perimeter is the distance that

01:03surrounds a shape. This castle's property is surrounded by a stone wall. The total length

01:09of the wall is about 200 yards, so the perimeter of the castle's property is 200 yards. A perimeter

01:15can be any shape, so long as it's closed. For example, here's a baseball field. The perimeter of

01:22the field has straight lines on its left and right sides, and a curved line along the outfield. If we

01:28just highlight this left foul line, we could say it's part of the perimeter, but it's not the whole

01:33perimeter. Many times, we see the perimeter as a wall or a fence or a row of trees that surround an

01:40area, like the perimeters for these fields. But sometimes, there's no object that makes up the

01:45perimeter. For example, we can tell the difference between these fields due to their colors. The

01:51distance around each field is its perimeter, and we could calculate the perimeter for each field,

01:56even though none of these fields has a fence, wall, or trees that separate them from other fields.

02:02Next, let's learn how to calculate the perimeter of a rectangle.

02:06A typical state exam question will describe an object like a rectangular field and tell you its size.

02:11Then the question will ask you what the total length of the fence is that surrounds that object.

02:17This is another way of asking you to calculate the perimeter of a rectangle.

02:21Here's a big soccer field. Its perimeter is in the shape of a rectangle.

02:25To calculate the perimeter, we need to add up the length of each side.

02:30This side is 100 yards long. This side is 50 yards long. This side is 100 yards long.

02:36And this side is 50 yards long. When we add them all up, we get a total of 300 yards.

02:43So the perimeter of this soccer field is 300 yards.

02:47Some of these soccer fields are bigger than others, but all are rectangles.

02:51Please note an important fact about any given rectangle. The short sides are the same length as

02:55each other. And the long sides are the same length as each other. This is an important fact

03:01about rectangles that will help us solve state exam problems. The length of this side is 50 yards.

03:07The length of this side is 25 yards. What's the perimeter of this soccer field?

03:15The key to figuring this out is to remember that for a rectangle, the long sides are both the same

03:20length as each other. And the short sides are the same length as each other. That means both of the

03:26long sides are 50 yards. And it means that both of the short sides are 25 yards. Now we can add up

03:32all the sides and we get 50 plus 50, plus 25, plus 25, which equals 150 yards.

03:42Next, let's learn how to calculate the perimeter of a triangle.

03:45Here's a cookie in the shape of a triangle. This side is 4 inches long. This side is 4 inches long.

03:52And this side is 2 inches long. What's the triangle's perimeter?

03:55Just as we did with the rectangle, we add up the length of each side. In this case, that's 4 inches,

04:05plus 4 inches, plus 2 inches, which equals 10 inches. The perimeter is 10 inches.

04:12Here's an equilateral triangle. One side is 10 feet. What is the perimeter of this triangle?

04:17An equilateral triangle is made of 3 sides that are all equal to each other. It's like this plastic

04:28frame surrounding these balls. In this example, that means that each of these sides is 10.

04:34To calculate the triangle's perimeter, we add up all the sides. That's 10, plus 10, plus 10,

04:40which equals 30. This triangle's perimeter is 30 feet.

04:44Our final topic is to talk about how to calculate the perimeter of shapes that don't have specific

04:50names. This pool's perimeter is not a rectangle. That's because this end has a curve instead of a

04:57straight line. We don't have a specific name for the pool's shape. So, we don't have a formula that

05:02lets us calculate the pool's perimeter. When we're given a shape that doesn't have a specific name,

05:07we can still calculate its perimeter by adding up the distance around it. For example,

05:12this garden is made up of several sections. In this example, we've labeled each side of this garden

05:18with its length and feet. We can add up all of these sides to calculate the perimeter.

05:23The perimeter for this garden is 92 feet. Thanks for your attention.

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