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Eligible Content M3.B.2.1.3
Help Me To: |
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Find the area of a figure drawn on a grid (only full grid blocks inside the figure.)
Did You Know?
You can find the area by counting the number of square units.
Check What You Know First
What is the area of this rectangle? |
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| What is the area of this square? |
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Key Vocabulary
Area is the number of square units needed to cover a flat surface.
A square unit is a square with a side length of one unit; used to measure area.
A rectangle is a plane figure with opposite sides that are equal and parallel, and with four right angles.
A square is a
polygon with 4 equal sides and 4 right angles.
Congruent is
having the same size or shape.
A plane figure is a closed figure that lies on a flat surface and is all in one plane.
A polygon is a closed figure with straight sides.
A right angle is an angle that forms a square corner and has a measure of 90 degrees.
Learn About It Now
Calculating the Area of a Rectangle on a Grid
Area is the number of square units needed to cover a flat surface.
To find the area of the rectangle in the problem below, count
the number of squares in the rectangle.
These squares represent square units. Area
is measured in square units.
The area of the rectangle is 18 square units.
There is another way to find the area of a rectangle.
To find the area of a rectangle, multiply the number
of rows times the number in each row
In the previous problem, there are 2 rows
times 9 squares in each row. 2
x 9 = 18 square units
2 x 9 = 18
square units
Number of rows Number
in each row Area
You can also use this formula for finding the area. You
can use this formula for finding the area
when you have a figure that
does not show the square units, only the numbers.
Area = length x width
or
A = l x w
A = 9 x 2 = 18 square cm.
Also use the formula when only given the numbers in a problem.
What is the area of a figure with a width of 5 inches and a length of 7 inches?
Area = length x width or
A = l x w
A = 7 x 5 = 35 square inches.
Calculating the Area of a Square on a Grid
To calculate the area of a square, you use the same rule and formula you use
in figuring out the area of a rectangle.
For the problem above, you can count the number of squares in the figure.
You can also multiply the number of rows times the number in each row.
The
area of the square is 64 square units.
You can also use this formula.
Area = length x width or
A = l x w
A = 8 x 8 = 64 square units
Once again, you can use the formula when only given the numbers in a problem.
What is the area of the following figure with a width of 8 units and a length of 8 units?
Area = length x width
or
A = l x w
A = 8 units x 8 units = 64
square units
More Practice With Finding the Area
Click below to practice calculating area of a rectangle.
(http://www.aaamath.com/B/geo78_x3.htm
Click below to practice calculating area of a square.
http://www.aaamath.com/B/geo78_x4.htm
Websites to Check Out For Extra Practice
Click below to practice calculating area and perimeter
http://www.mathplayground.com/InteractiveGeometry.html
Click below to play the Shape Surveyor game
while finding area and perimeter
http://www.funbrain.com/poly/index.html
Instructions for Shape Surveyor
You will be shown a rectangle with the dimensions labeled.
You must calculate the area or perimeter of the rectangle.
For each problem you get correct, you will receive a piece of an archeological
puzzle.
The game is over when you get all the puzzle pieces.