Measuring rectangles with different unit squares

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Maths3rd grade math3:043 check-ins

About this video

Two rectangles with the same area are measured using different square units. The top one is tiled with square feet and has an area of 12 square feet; the bottom one is tiled with a made-up, bigger unit called a square voot and has an area of 3 square veet. Since 4 square feet fit in one square voot, both measurements describe the same area.

You'll be able to

  • measure the area of a rectangle by tiling it with a given square unit.
  • explain why the same area gives a smaller number when measured with a bigger unit.
  • check that two measurements of the same area agree.

Key words

square foot
A square that is 1 foot tall and 1 foot wide, used to measure area.
square unit
A square of a chosen size that we count to measure area.
area
How much space a shape covers, counted in square units.
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?

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