8.10 Area & Perimeter

SOL

The student will solve area and perimeter problems, including practical problems, involving composite plane figures.

Essential Knowledge

• Perimeter: the path / distance around a figure (called “circumference” for circles).

• Area: the amount of space inside a two-dimensional shape.

• Composite figures: shapes/figures that are made by combining triangles, rectangles, squares, trapezoids, parallelograms, circles, and/or semi-circles.

• Find the area of a composite figure by (1) breaking the figure up into shapes you can find the area of, and (2) find the area of those smaller shapes. Be sure (3) to add the areas of each section together at the end.

  • For a semi-circle, you will need to cut the area / circumference of a circle in half. You can do this by (a) dividing by 2, or (b) multiplying by 1/2.

Target Skills

• Break a composite figure into triangles, rectangles, squares, trapezoids, parallelograms, circles, and/or semi-circles.

• Figure out the area of each section of the composite figure & add them together to find the area of the entire shape.

• Use the sides of each section to figure out the length of each side of the figure & add them together to find the perimeter of the entire shape.

• Calculate the difference (subtraction) in area between 2 or more shapes.

Desmos Tips

IXL Topics

• 6.FF.1-13, 22-24

• 7.AA.1-6, 15-19

• 8.T.1-7

• A.F.1-3, 10

7th grade actually has the best topics for this unit, especially 7.AA.15-19.

Websites (Videos)

• Area of Composite Figures (YouTube)

• Area of Composite Shapes (Khan Academy)

• Art of Problem-Solving

  • length & perimeter

  • areas of rectangles & right triangles

  • area of an acute triangle

  • area of an obtuse triangle

  • area problem solving (part 1)

  • area problem solving (part 2)

  • introduction to circles

  • area of a circle (part 1)

  • area of a circle (part 2)

  • funky area

Websites (Practice)

• Khan Academy

  • Area of Composite Shapes

  • Area Challenge

Websites (Games)

• Learn Alberta

  • exploring composite figures

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• Math Games (listed in order of difficulty)

  • 2. 4 area with unit squares

  • 3.5 area with unit squares and units

  • 3.14 area with unit squares

  • 3.15 area of rectangles

  • 3.16 area of squares and rectangles

  • 3.17 area of complex figures

  • 3.18 fnd the perimeter

  • 3.19 find the missing side

  • 3.20 compare area & perimeter of 2 figures

  • 3.21 use area & perimeter to determine the cost

  • 3.22 relationship between area & perimeter

  • 3.91 area of squares & rectangles (review)

  • 4.17 relationship between area & perimeter

  • 4.18 use area & perimeter to determine the cost

  • 4.25 compare area & perimeter of 2 figures

  • 4.113 perimeter with unit squares

  • 4.117 area of squares and rectangles

  • 5.115 area of squares & rectangles

  • 6.106 area of complex figures

  • 6.107 compare area & perimeter of 2 figures

  • 6.121 area of right triangles

  • 7.1 calculate area, radius, circumference of circles

  • 7.3 parts of a circle

  • 7.18 area of triangles & trapezoids

  • 7.121 area of rectangles and parallelograms

  • 7.146 circles

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