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## 3rd grade

### Course: 3rd grade > Unit 10

Lesson 3: Area formula intuition# Transitioning from unit squares to area formula

Lindsay finds the area of a rectangle both by counting unit squares and multiplying side lengths. Created by Lindsay Spears.

## Want to join the conversation?

- I'm super confused. I CAN'T FIGURE THIS OUT! Can you help me? I'm having trouble understanding any of this. Could you explain it more?(13 votes)
- So how we are doing this is like we are multiplying so take a sheet of paper and draw a square not a perfect one but as good as you can, Then measure it so you will have to measure the length and the width guys, then you have to pick the size of the square you want to measure with , i example a centimeter so my square has two dimonsons example 6 and 7 multiply them 6x7=42 so my square is 42 centimeters , got it ?(15 votes)

- upvote me if you like Jesus(13 votes)
- help me understand this!(9 votes)
- count the one side and the top. say its 2 and 4. do 2x4 and you have the area(6 votes)

- that's true the only thing is when calculating the area of a square you can simply multiply one of the sides by itself since you know the other sides are all the same. and does it matter if it's a rectangle or a square in ares wouldn't still be length times width?(5 votes)
- That's correct. Squares
*are*rectangles, but rectangles are not squares. Therefore, when finding the area of a rectangle, you can simply multiply the length by the width.(8 votes)

- how is this gonna help us in life?(3 votes)
- You need to know how much paint to buy to paint rooms or carpet or tiling for floors. How much dirt you might need to build a garden, there are a lot of applications in life.(9 votes)

- they are soooo long(6 votes)
- yes that is true(2 votes)

- Its Supercalifragilisticexpialidocious even though the sound of it is quite atrocious if you say it loud enough you'll only sound precocious Supercalifragilisticexpialidocious. um diddle diddle um diddle ay um diddle diddle um diddle ay,Because I was afraid to speak when I was just a lad

Me father gave me nose a tweak, told me I was bad

But then one day I learned a word that saved me achin' nose

The biggest word you ever heard and this is how it goes

Oh, supercalifragilisticexpialidocious

Even though the sound of it is something quite atrocious

If you say it loud enough you'll always sound precocious

Supercalifragilisticexpialidocious

Um-dittle-ittl-um-dittle-I

Um-dittle-ittl-um-dittle-I

Um-dittle-ittl-um-dittle-I

Um-dittle-ittl-um-dittle-I

He traveled all around the world and everywhere he went

He'd use his word and all would say there goes a clever gent

When dukes or Maharajas pass the time of day with me

I say me special word and then they ask me out to tea (woo)

Supercalifragilisticexpialidocious

Even though the sound of it is something quite atrocious

If you say it loud enough you'll always sound precocious

Supercalifragilisticexpialidocious

Um-dittle-ittl-um-dittle-I

Um-dittle-ittl-um-dittle-I

You know you can say it backwards which is

Dociousaliexpisticfragicalirupus

But that's going a bit too far, don't you think?

Indubitably

So when the cat has got your tongue there's no need for dismay (here-ye)

Just summon up this word and then you've got a lot to say

But better use it carefully or it could change your life

For example

Yes?

One night, I said it to me girl and now me girl's me wife

Oh, and a lovely thing she is, too

She's

Supercalifragilisticexpialidocious

Supercalifragilisticexpialidocious

Supercalifragilisticexpialidocious

Supercalifragilisticexpialidocious

Source: LyricFind(6 votes) - - [Voiceover] This square is 1 square unit, so what is the area of Rectangle A? The first thing we're told is that each of these little squares equal 1 square unit, and then, we're asked to find the area of Rectangle A. Here's Rectangle A, and area is the space that it covers. So how much space does Rectangle A cover? How many square units does Rectangle A cover? One way to answer that would be count how many square units it covers, except they've covered up our square units. So, one idea's we could draw them back. Say you cover'em up, we'll draw them back in. So goin' like this, connect all these, and then, we should be able to count our square units. So we have one, two, three, four, five six, seven, eight, nine, 10, 11, 12. 12 square units. Rectangle A covers 12 square units, so it has an area of 12 square units. But this isn't the only way that we could've solved this. We could've also said, we could've also looked at this and said, okay, this top row is four square units long. One, two, three, four, has a length of four units. So that means the top row will have one, two, three, four square units inside of it. And then we coulda looked over on the side, over here, and said, well, how many rows of four will they'll be? It'll be one, two, three rows of four. So we'll have this row of four, and then a second row of four, and a third. So three times, we will have four square units. There's four square units at the top, another in the middle, and another at the bottom. Three times, we will have four square units. Or, we could go even farther than that. So we coulda done three times four, or we could look at this and say, okay, here's one column. This column has three square units. It has a length of three. One, two, three. How many of these columns like this will there be? There'll be one, two, three, four, 'cause our length here at the top is four. So, this time, four times, we will see three square units. One, two, three, and we'll see that one, two, three, four times. So, no matter which of these we solved, whether we counted the square units like in the beginning, or we multiplied the side lengths, the three and the four, in every case, we're gonna find that this equals 12 square units. The area of Rectangle A is 12 square units because it covers 12 square units.(5 votes)
- Why always so confusing(5 votes)
- This is really easy. Is it even high school geometry?(3 votes)
- Finding the area of a rectangle is much lower than high school level.

High school includes finding perimeters & areas of triangles, trapezoids, parallelograms, & circles, finding surface areas & volumes of prisms, cylinders, pyramids, cones, & spheres, finding lengths of missing sides of right triangles (Pythagorean theorem), using side length ratios in similar triangles to find missing sides, using angle relationships for parallel lines, intersecting lines, perpendicular lines, & polygons to find missing angles, using properties of circles to find missing lengths and/or angles, writing proofs using definitions, properties, postulates, & theorems, and more!

This seems like a lot, but as you build your understanding of math through the lower grade levels, you will become more prepared for high school geometry.

Have a blessed, wonderful day!(4 votes)

## Video transcript

- [Voiceover] This
square is 1 square unit, so what is the area of Rectangle A? The first thing we're told is that each of these little
squares equal 1 square unit, and then, we're asked to
find the area of Rectangle A. Here's Rectangle A, and area
is the space that it covers. So how much space does Rectangle A cover? How many square units
does Rectangle A cover? One way to answer that would be count how many square units it covers, except they've covered
up our square units. So, one idea's we could draw them back. Say you cover'em up,
we'll draw them back in. So goin' like this, connect all these, and then, we should be able
to count our square units. So we have one, two,
three, four, five six, seven, eight, nine, 10, 11, 12. 12 square units. Rectangle A covers 12 square units, so it has an area of 12 square units. But this isn't the only way
that we could've solved this. We could've also said, we
could've also looked at this and said, okay, this top row
is four square units long. One, two, three, four, has
a length of four units. So that means the top row will have one, two, three, four
square units inside of it. And then we coulda looked
over on the side, over here, and said, well, how many
rows of four will they'll be? It'll be one, two, three rows of four. So we'll have this row of four, and then a second row
of four, and a third. So three times, we will
have four square units. There's four square units at the top, another in the middle,
and another at the bottom. Three times, we will
have four square units. Or, we could go even farther than that. So we coulda done three times
four, or we could look at this and say, okay, here's one column. This column has three square units. It has a length of three. One, two, three. How many of these columns
like this will there be? There'll be one, two, three, four, 'cause our length here at the top is four. So, this time, four times, we
will see three square units. One, two, three, and we'll see that one, two, three, four times. So, no matter which of these we solved, whether we counted the square
units like in the beginning, or we multiplied the side
lengths, the three and the four, in every case, we're gonna find that this equals 12 square units. The area of Rectangle A is 12 square units because it covers 12 square units.