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## 3rd grade

### Course: 3rd grade > Unit 10

Lesson 2: Count unit squares to find area- Intro to area and unit squares
- Measuring rectangles with different unit squares
- Find area by counting unit squares
- Compare area with unit squares
- Creating rectangles with a given area 1
- Creating rectangles with a given area 2
- Create rectangles with a given area

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# Measuring rectangles with different unit squares

Sal finds area of a rectangle with different sized units. Created by Sal Khan.

## Want to join the conversation?

- at2:15what is a furgle(22 votes)
- A
**furgle**is a made-up unit of measurement.

1 furgle = 2 feet

At2:23, Sal comments that "one furgle" is something that he made up just for this video, so that we can practice measuring identical rectangles with two*different*units: feet & furgles.(19 votes)

- So, can you just use all six of the mini units that are 1 square foot and make a big square and do it the same for the other side? It will have the same amount of space, but different areas. Can we do that if it is possible?(10 votes)
- yes you can ,but both will have the same area because it has the same amount of space the only difference is that they will be measured in different square units

for example the measure of a square, measured in mm will be the same as measure in cm just that there will be a difference in number because u r using 2 different units but when u convert the answer u get in cm to mm the area will be the same

hope this helped(9 votes)

- What is a "voot" as used in the video at @0:58seconds?(9 votes)
- A rectangle has an area of 18"and the height of the rectangle is 6 inches what is the length of the rectangle(6 votes)
- Remember that the area of a rectangle is its length x its height. So, we know the formula is (l x h = a).

Let's plug in our known values: (l x 6 = 18)

Let's rearrange to isolate the variable: (18 / 6 = l)

Let's solve for the length: (l = 3)

So, the length of the rectangle is 3 inches. It's simple algebra! Let me know if you have further questions.(7 votes)

- how does area help the real world(4 votes)
- It helps in panting spaces in a lot or planting seeds,and placing tiles in your house.(6 votes)

- At2:02what is a feet? And why does it sound weird?(4 votes)
- It sounds weird because Sal is actually saying 'veet' and not 'feet.' Presumably 'veet' is the plural form of 'voot.' Sal is comparing feet and veet (a fictional unit) to show how we can use different units of area to measure the same object, but we have to take into account that the units are not of equal size.(7 votes)

- What is a furgle(4 votes)
- A furgle is a made-up unit of measurement.

1 furgle = 2 feet

At2:23, Sal comments that "one furgle" is something that he made up just for this video, so that we can practice measuring identical rectangles with two different units: feet & furgles.(6 votes)

- This is so easy for me because i can just type this

So we've got two figures right over here, and I want to think about how much space they take up on your screen. And this idea of how much space something takes up on a surface, this idea is area. So right when you look at it, it looks pretty clear that this purple figure takes up more space on my screen than this blue figure. But how do we actually measure it? How do we actually know how much more area this purple figure takes up than this blue one? Well, one way to do it would be to define a unit amount of area. So, for example, I could create a square right over here, and this square, whatever units we're using, we could say it's a one unit. So if its width right over here is one unit and its height right over here is one unit, we could call this a unit square. And so one way to measure the area of these figures is to figure out how many unit squares I could cover this thing with without overlapping and while staying in the boundaries. So let's try to do that. Let's try to cover each of these with unit squares, and essentially we'll have a measure of area. So I'll start with this blue one. So we could put 1, 2, 3, 3, 4, 5, five unit squares. Let me write this down. So we got 1, 2, 3, 4, 5 unit squares, and I could draw the boundary between those unit squares a little bit clearer. So we have 5 unit squares. And so we could say that this figure right over here has an area. The area is 5. We could say 5 unit squares. The more typical way of saying it is that you have 5 square units. That's the area over here. Now, let's do the same thing with this purple figure. So with the purple figure, I could put 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 of these unit squares. I can cover it. They're not overlapping, or I'm trying pretty close to not make them overlap. You see, you can fit 10 of them. And let me draw the boundary between them, so you can see a little bit clearer. So that's the boundary between my unit squares. So I think-- there you go. And we can count them. We have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. So we could say the area here-- and let me actually divide these with the black boundary, too. It makes it a little bit clearer than that blue. So the area here for the purple figure, we could say, so the area here is equal to 10. 10 square, 10 square units. So what we have here, we have an idea of how much space does something take up on a surface. And you could eyeball it, and say, hey, this takes up more space. But now we've come up with a way of measuring it. We can define a unit square. Here it's a 1 unit by 1 unit. In the future we'll see that it could be a unit centimeter. It could be a 1 centimeter by 1 centimeter squared. It could be a 1 meter by 1 meter squared. It could be a 1 foot by 1 foot square, but then we can use that to actually measure the area of things. This thing has an area of 5 square units. This thing has an area of 10 square units. So this one we can actually say has twice the area. The purple figure had twice the area-- it's 10 square units-- as the blue figure. It takes up twice the amount of space on the screen.

Plz give me 50+ votes then i will give you a lot of votes(3 votes)- ws wwwiweiweiweiiiiiiiiiisw swn swnwsnnsw n swn wsn sw nwsn wns n wsn swn wsnwnwsnjwnjswjwnjwnssw sw nsw ws ws ws

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- it was last talking about area. area is the space in a shape it takes up.(4 votes)
- at3:19does it have to be square?(3 votes)
- i guess so :)(3 votes)

## Video transcript

- What we're going to do in this video is look at two rectangles
that have the exact same area, and we're going to measure each of them with a different square unit. So this top unit right over
here, this is a square foot. So that means its height is one foot and it's width right here is one foot. Now, this is square unit over here, this is completely made up. And I'm going to call
this a voot or a voot. So, this right over here is one voot and this over here,
the width, is one voot. So this entire thing is a one square voot, while this top one, of
course, is one square voot. Now, let's measure the top rectangle in terms of square feet, and let's measure the bottom
rectangle in terms of square, I guess I could say veet,
(chuckles) all right. So first the top rectangle. So we have one, two square feet, three square feet, four square feet, five square feet, and then we have, looks
like six square feet. And then we're gonna need to
have another six square feet down here. So that's seven, eight,
nine, 10, 11, and 12. So when I tile these square feet onto our original rectangle, it looks like we have 12 square feet. And so I could write it's area
like this, 12 square feet. Now what about this one in terms of veet? You could have a square
voot or many square veet. Let me do the same exercise here. That's one square voot, this is two square veet, I could say, and then this is three square veet. So the same area could
either be 12 square feet or it could be three square veet. And I want you to think about
whether that makes sense. Think about how many square feet would make up one square voot. In fact, we can figure that
out on our own right over here. So that's one square foot,
this is two square feet, this is three square feet,
and then four square feet. So it looks like four square
feet make up one square voot. And so think about, does it make sense that three square veet is the same thing as 12 square feet?