yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Decomposing shapes to find area (grids) | Math | 3rd grade | Khan Academy


2m read
·Nov 11, 2024

Each small square in the diagram has a side length of one centimeter. So, what is the area of the figure? We have this figure down here in blue, and we want to know its area. Area is the total space it covers, and we're also told that each of these little squares has a side length of one centimeter.

That means each of these squares is one square centimeter. We can find the area by seeing how many square centimeters this figure covers. One way would be just to try to draw the little square centimeters and count them. There’s one square centimeter, there’s two, and so on, and keep counting them all the way through.

Or, what we could do is look at this and try to break it into two shapes. We can say down here into two rectangles. Down here, we have one rectangle, and up here, we have a second rectangle. Then we can find the area of each rectangle and add it together to find the total area that the figure covers.

Down here on the bottom, we have two rows of unit squares, and each of those has one, two, three, four, five, six, seven. So, one, two, three, four, five, six, seven. So, there are two rows of seven unit squares or seven square centimeters. The bottom rectangle is made up of 14 square centimeters. It covers 14 square centimeters.

Now, for the top rectangle, let’s see: we have one row, two, three, four, five rows, and each of those rows has one, two square centimeters. So, we have five rows of two square centimeters or 10. This top rectangle here that we have in blue covers 10 square centimeters.

Plus, the bottom rectangle that we outlined in green covers 14 square centimeters. So, in total, the entire figure covers 24 square centimeters. Thus, 24 square centimeters is our area, because area is how much space it covers, and we figured out that it covered 24 square centimeters.

More Articles

View All
Lecture 17 - How to Design Hardware Products (Hosain Rahman)
Very exciting! And thank you, Sam, uh, for having me. Sam and I have known each other for a long time because we were fellow Sequoia companies, and we met in the early days of when he was on his, uh, company journey. So it’s cool! So what he asked me to t…
Investments and retirement unit overview | Teacher Resources | Financial Literacy | Khan Academy
Hello teachers! Welcome to the unit on investments and retirement. As always, I encourage you to go through the unit yourself. If you have limited time, at least go through the exercises and the unit test to refresh both your own understanding of this mat…
James Manyika on how the pandemic has accelerated the future of work | Homeroom with Sal
Hi everyone! Welcome to our daily homeroom. I’m very excited about the guest we have today. Before we jump into that conversation, I will give my standard announcement. I want to remind everyone that Khan Academy is a not-for-profit organization that can…
A Bad Situation | Badlands, Texas
Have a visit with this [Applause] fella 211, so I’m going to be out South 118. How you doing? Just ging away? Well, the reason why I stopped you, you’re speeding 85 in a 70. I just am so sorry. I was so sure when they came back with a not-guilty verdict,…
What Happens If We Throw an Elephant From a Skyscraper? Life & Size 1
Let’s start this video by throwing a mouse, a dog, and an elephant from a skyscraper onto something soft. Let’s say, a stack of mattresses. The mouse lands and is stunned for a moment before it shakes itself off and walks away pretty annoyed, because that…
Generalizabilty of survey results example | AP Statistics | Khan Academy
Niketi took a random sample of 10 countries to study fertility rate and life expectancy. She noticed a strong negative linear relationship between those variables in the sample data. Here is computer output from a least squares regression analysis for usi…