Main content
Course: 3rd grade > Unit 10
Lesson 4: Multiply to find areaArea of rectangles review
Review the basics of area of rectangles and try some practice problems.
What is area?
Area is the space inside of a two-dimensional shape. We can also think of area as the amount of space a shape covers.
For example, the rectangle below has an area of square units because it covers square units.
Want to learn more about the concept of area? Check out this video.
Area of a rectangle formula
To find the area of a rectangle, we multiply the length of the rectangle by the width of the rectangle.
Want to know why this formula works? Check out this video.
Example 1:
Example 2:
Practice set 1: Multiply to find area
Want to try some more area of rectangle problems? Check out this exercise:
Area of rectangles
Area of rectangles
Practice set 2: Count square units to find area
Want to try some more unit square problems? Check out these exercises:
Find area by counting unit squares
Transition from unit squares to area formula
Create rectangles with a given area
Find area by counting unit squares
Transition from unit squares to area formula
Create rectangles with a given area
Practice set 3: Challenge items
Want to try some more challenge items? Check out these exercises:
Find a missing side length when given area
Decompose figures to find area 1
Decompose figures to find area 2
Find a missing side length when given area
Decompose figures to find area 1
Decompose figures to find area 2
Want to join the conversation?
- If a shape is uneven, how can we work out the area?(12 votes)
- Try to break the shape into simpler shapes - ones that have areas that are easy to calculate. Calculate the area of each smaller shape, then add them all together to get the area of the whole shape.
(This is what they did up above when they had us count squares to figure out the area of the big shape.)
Each square is 1x1, so the area of each square is one.
(First step: calculating the area of the smaller shapes.)
Then when we counted all the squares, the total number of squares was also the area of the shape.
(Second step: add together all the areas of the smaller shapes.)
Hope this helps!(30 votes)
- How do you figure out square feet? I need to calculate the area of a back splash so i can purchase wall tiles.(31 votes)
- for tiles times the length by the width and you get the area(19 votes)
- what if you reverse the numbers of the area would the answers still be the same?🤔(10 votes)
- It would! For a rectangle, it doesn't really matter which side is length and which side is width. Because the order in which you multiply two numbers doesn't matter, the area is the same both ways. You can think of just turning a rectangle from the skinny side being horizontal to it being vertical. Nothing changes about the amount of space the rectangle takes up, so its area is the same :)(13 votes)
- so let me get this clear, you have to multiply to find the answer?(2 votes)
- To find the area of a rectangle, multiply the length by the width, yes.(13 votes)
- Which would cover more of my floor, a 5m x 6m rug, or a 4m x 8m rug?(1 vote)
- 4m x 8m rug, cause the area of that rug is 32, in contrast to the 5m x 6m rug which is 30.(6 votes)
- How are u supposed to do Quizzes if u don't know the awnser(1 vote)
- Is there a formula for a 3d shape?(0 votes)
- Good question! Just like area measures the amount of space (number of unit squares) inside a 2d shape, volume measures the amount of space (number of unit cubes) inside a 3d shape.
The formula for the volume of a rectangular solid (box) is almost like the formula for the area of a rectangle, except that one more dimension (the height) is multiplied. So just as the area of a rectangle is length times width, the volume of a rectangular solid is length times width times height.(4 votes)
- What do you do when you have more than 2 missing labels for how many cm. or in. and ft.?(1 vote)
- In Practice 3, the cat picture only has one label. You really only need the area and one side length to solve for all of the lengths.
In the example, the area is 56 cm. One side of the picture is 7 cm. Divide the area by the length, since you know that the product of the two sides will be 56.
56 ÷ 7 = 8.
The missing side is 8 cm.(1 vote)
- i don't really get the first problem in 2A. Cant someone please explain it?(1 vote)
- The shape with the blue outline covers an area equal to that of 11 squares.
Each square has an area of 1 square unit.
So, the area of the shape is 11 square units.(1 vote)
- What are some key words to know to find area?(1 vote)