Composite Area Written by: James Wiens Newton, Kansas 8cm 5

Instructor Notes Subject Area(s): Math Grade level: 7 th grade Lesson Length: 50 minute class period Synopsis: Solve for area of composite figures Objective/goals: Students will find the area of composite figures by breaking them into common shapes with formulas such as triangles, quadrilaterals and circles.

Standard: c. Kansas standard A1c▲ ■ finding perimeter and area of two- dimensional composite figures of squares, rectangles, and triangles (2.4.A1h), e.g., the front of a barn is rectangular in shape with a height of 10 feet and a width of 48 feet. Above the rectangle is a triangle that is 7 feet high with sides 25 feet long. What is the area of the front of the barn? Pre-requisite skills: Vocabulary – Area, base, height, triangle, paralellogram, trapezoid, pi, radius, circle. TurningPoint functions: standard question slides Materials: All instructional points and practice problems are provided within the power point slides. Practice questions are designed to be used with the TurningPoint clickers. Instructor Notes

Lesson Outline I.Warm-up: find area of basic shapes II.Definitions / Key Concepts III.Setting the Stage: Video lesson IV.Guided practice: Turning Point Questions V.Independent practice: Paper & pencil VI.Closure: Write about area

Find the area. 8in 11in a)19 in 2 b)44 in 2 c)88 in 2 Countdown 10

Answer Area parallelogram = base x height A = bh A = 8 (11) A = 88 in. 2

Find the area. a)30 in 2 b)60 in 2 c)120 in 2 6in 10in Countdown 10

Answer Area triangle = ½ (base x height) A = ½ bh A = ½ (6)(10) A = ½ (60) A = 30 in. 2

Find the area. (Use 3.14 for π) a)62.8 in 2 b)314 in 2 c)31.4 in 2 10in Countdown 10

Answer Area circle = π r 2 A = π r 2 A = π (10) 2 A = π (100) A = 314 in. 2

Definition Area of complex figures To find the area of a complex figure, break the shape into two or more simple figures. Find the area for the simple figures then combine those amounts to find the total of the complex figure.

Setting the Stage How much area does the blue figure cover?

Answer A = bh A= 4 (9) A = 36 in. 2 A = ½ bh A = ½ (4)(3) A = ½ (12) A = 6 in. 2 Final Answer: = 42 in. 2

Video Clip Lesson from Teacher Tube Click on the link at the right to access a lesson about area of composite figures from Holt Mathematics. Click here to see the lesson

What is the area of this figure? A.36 cm 2 B.54 cm 2 C.45 cm 2 D.18 cm cm Countdown 10

What is the area of this figure rounded to the nearest cm 2 ? (Use 3.14 for π) A.40 cm 2 B.90 cm 2 C.126 cm 2 D.241 cm 2 8cm 5 Countdown 10

What is the area of this figure? A.114 cm 2 B.108 cm 2 C.87 cm 2 D.72 cm Countdown 10

Independent Practice - Find the area of each figure rounded to the nearest foot (All units in feet ). B. A. D. C

Answer Key for Independent Practice A. = 200 ft. 2 B. = 210 ft. 2 C. = 8500 ft. 2 D. = 130 ft. 2

Closure / Summary Explain how finding the area of a right angle trapezoid is the same as using the sum of the areas of a triangle and a rectangle.

References Video clip from slide # 14 found at son_videos/msm1/player.html?contentSrc =6072/6072.xml (Holt McDougal math series, Houghton Mifflin Harcourt.) son_videos/msm1/player.html?contentSrc =6072/6072.xml Remainder of lesson designed and written by James Wiens, 7 th grade math teacher, Newton Kansas.