GEOMETRYMeasurement

Terry Scates

Newton, Kansas

Instructor Notes

• Subject Area(s): Special Education Resource Math

• Grade level: 7th grade • Lesson Length: 50 minute class period• Synopsis: Solve for area of circles, triangles,

and parallelograms. • Objective/goals: Students will find the area

formulas for circles, squares, rectangles, triangles, and parallelograms (2.4.K1h).

• Kansas State Standard/Benchmark/Indicator; M.7.3.2.K4

Standard: Geometry

Benchmark: Measurement and Estimation

Indicator: Knows and uses perimeter and area formulas for circles, squares, rectangles, triangles, and parallelograms

• Explanation of Indicator

Find perimeter (distance around the outside) and area (square units of space inside) of various shapes

• Pre-requisite skills: Vocabulary – Area, base, height, triangle, parallelogram, 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

1. Warm-up: find area of basic shapes

2. Definitions / Key Concepts

3. Setting the Stage: Video lesson

4. Guided practice: Turning Point Questions

5. Independent practice: Paper & pencil

6. Closure: In the room find a triangle, a quadrilateral, or a circle. Using a ruler, yard stick, or metric stick determine the area of the shape you find.

Area of a Parallelogram

The area A of a parallelogram equals

the product (product means multiply) of

it’s base b and it’s height h.

Area=base X height

A=bh

The base is any side of a parallelogram.

Base

Base

The height is the length of the segment perpendicular to the base with endpoints on opposite sides.

height

Find the area of this parallelogram

8in

11in

19 in2

44 in2

88 in2

33%33%33%

a) 19 in2

b) 44 in2

c) 88 in2

CountdownCountdown

10

AnswerThe area A of a parallelogram equals

the product (product means multiply) of

it’s base b and it’s height h.

Area=base X height

A=bh or A=b X hA = 8(11) or A = 8 X 11

A = 88 in.2

Area of a Triangle

The area A of a triangle equals half (1/2) the

product (product means multiply) of it’s

base b and it’s height h.

Area = ½ X b X h

A=1/2bh

The height is the distance from a base

to the opposite vertex.

. height

The base of a triangle can beany of its sides.

base base

base

Find the area.

30

in2

60

in2

120

in2

33%33%33%

6in

10in

a) 30 in2

b) 60 in2

c) 120 in2

CountdownCountdown

10

AnswerThe area A of a triangle equals half (1/2)

The product (product means multiply) of

it’s base b and it’s height h.

Area = ½ X b X h or Area = .5 X b X h

A=1/2bh or A=.5bh

A = ½ (6)(10) or A = .5 X 6 X 10

A = ½ (60) or A = .5 X 60

A = 30 in.2

Area of a CircleThe area A of a circle equals the product(product means multiply) of pi (π) and thesquare of it’s radius r.

Area = πr2

(Pi = π = 3.14)

A=3.14 X r2 Radius

The radius r is the distance from the center to any point on the circle.

radius

Find the area. (Use 3.14 for π)

62.

8 in

2

314

in2

31.

4 in

2

33%33%33%

10in

a) 62.8 in2

b) 314 in2

c) 31.4 in2

CountdownCountdown

10

AnswerThe area A of a circle equals the product

(product means multiply) of pi (π) and thesquare of it’s radius r.

Area = π r2

A=3.14 X r2

A = 3.14 (10)2

A = 3.14 (100)

A = 314 in.2

Closure / Summary

In the room find a triangle, a

quadrilateral, or a circle. Using a ruler,

yard stick, or metric stick determine the

area of the shape you find.

References

Glencoe McGraw-Hill Math Connects Course 2, Study Guide and Intervention

and Practice Workbook, 2008.

Wiens, James, Composite Areas, PowerPoint presentation, December 2008.