Assessment Design

• Mathematics
• 3rd Grade

Calculating the Area of a Rectangle

What is Area?

The area of a shape measures the size of the inside of a shape. This means it measures how big the surface is.

Method Number One

To find the area of this rectangle, one way that we can do this is to divide the rectangle into units and count the total number of units.

If we have the measurements of a rectangle, what is another way to find the area?

Multiplying the Dimensions

Another way of finding the area is to use multiplication. If you see this rectangle, do you know how could you use multiplication to find its area?

Using Multiplication

To calculate the area of this rectangle, we can multiply the length (8cm) by the height (3cm). This tells us that the rectangle has an area of 24 square centimeters.

8 x 3 = 24

If a rectangle has a height of 6mm and a length of 9mm, what is the area?

1. 15 square mm
2. 54 square mm
3. 30 square mm
4. 32 square mm

Using Multiplication

To find the area of this rectangle, we can multiply the height (6mm) by the length (9mm) to find that the area of this rectangle is 54 square mm.

6 x 9 = 54

Peer Discussions/Quizzes

Use this Google Doc to ask and respond to questions about area. Write in whatever questions you have about the subject. If you see a question you know the answer to, write your answer!

https://docs.google.com/document/d/1WmotiFB_RXZHcGAz7F0mIfMWCEDOcPkJ1x2PoguSG98/edit?usp=sharing