Geometry: Circling the Bases - Level 1
Lesson 3 – Pre-Visit
Perimeter and Area
Objective: Students will be able to:
• Distinguish between area and perimeter.
• Calculate the perimeter of a polygon whose side lengths are given or can be
determined.
• Calculate the area of a polygon whose side lengths are given or can be
determined.
Time Required: 1 class period
Materials Needed:
- Copies of the “Shape & Angle Review” worksheet (included) – 1 for each student
- Copies of the “World’s Biggest Fan” worksheet (included) – 1 for each student
- Students’ Geometry Dictionaries started in Lesson 1
- Rulers
- Protractors
- Graph Paper
- Pencils
Vocabulary:
Area - The surface inside a figure or shape
Length - The measured distance from one end to the other of the longer side of an
object
Line Segment – A part of a straight line included between two points
Perimeter - The distance around the outside of a polygon
Polygon – A closed figure made up of line segments
Width - The measured distance from one end to the other of the shorter side of an
object
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Geometry: Circling the Bases - Level 1
Applicable Common Core State Standards:
CCSS.Math.Content.3.MD.C.5 Recognize area as an attribute of plane figures and
understand concepts of area measurement.
• CCSS.Math.Content.3.MD.C.5a A square with side length 1 unit, called “a unit
square,” is said to have “one square unit” of area, and can be used to measure
area.
• CCSS.Math.Content.3.MD.C.5b A plane figure which can be covered without
gaps or overlaps by n unit squares is said to have an area of n square units.
CCSS.Math.Content.3.MD.C.6 Measure areas by counting unit squares (square cm,
square m, square in, square ft, and improvised units).
CCSS.Math.Content.3.MD.C.7 Relate area to the operations of multiplication and
addition.
• CCSS.Math.Content.3.MD.C.7b Multiply side lengths to find areas of rectangles
with whole-number side lengths in the context of solving real world and
mathematical problems, and represent whole-number products as rectangular
areas in mathematical reasoning.
CCSS.Math.Content.3.MD.D.8 Solve real world and mathematical problems involving
perimeters of polygons, including finding the perimeter given the side lengths, finding
an unknown side length, and exhibiting rectangles with the same perimeter and
different areas or with the same area and different perimeters.
CCSS.Math.Content.4.MD.A.3 Apply the area and perimeter formulas for rectangles in
real world and mathematical problems.
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Geometry: Circling the Bases - Level 1
Lesson & Activity
1. Begin the lesson by providing students with copies of the “Shape & Angle Review”
worksheet (included).
2. Have students identify different shapes and angles evident on a baseball field as a
warm-up for this lesson.
3. Explain that today you will be discussing different ways to measure shapes. Review
the following definitions:
- Length - The measured distance from one end to the other of the longer side
of an object
- Width - The measured distance from one end to the other of the shorter side
of an object
4. Have students add “length” and “width” (and all following vocabulary words) to
their Geometry Dictionaries.
5. Explain that perimeter is the measure of the distance around the outside of a
polygon. It is found by adding the lengths of all sides of a figure. Sometimes the
lengths of each side are given; sometimes the lengths will need to be measured.
6. On the board, draw a rectangle labeled with a length of 4 feet and width of 3 feet.
Then draw a right triangle with a base of 4 feet, height of 3 feet, and a hypotenuse
of 5 feet. Demonstrate that to measure the perimeter of any polygon, the lengths of
each side are added.
7. Provide students with the formula to find the perimeter of a rectangle:
Perimeter = 2 x (length + width)
8. Remind students that rectangles have two pairs of matching sides. Opposite sides
are equal. Squares have four equal sides, so if the length of one side is known, the
lengths of all other sides are known as well.
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Geometry: Circling the Bases - Level 1
9. Draw a diagram of a baseball field as shown below. Discuss that the infield is
commonly known as the “baseball diamond.” Home plate, first, second, and third
bases make up the four points of the diamond.
10. Ask students to identify what other shape could be used to describe the baseball
diamond.
11. The baseball “diamond” is a square. Review that a square is a quadrilateral with all
sides of equal length and all angles measuring 90 degrees. Point out that each side
of the baseball diamond measures 90 feet. Have students determine the perimeter
of the baseball diamond.
90 ft.
90 ft.
90 ft.
90 ft.
12. Review that 90’ + 90’ + 90’ + 90’ = 360’.
13. Explain that the area of a figure measures the amount of space inside it. Area is
measured using square units. For example, if inches are used to measure length,
then the area will be measured in square inches.
14. Show students that square units are indicated with a superscript 2 following the
units of measure. For example, 90’².
15. Provide students with the formula to find an object’s area:
Area = length x width
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Geometry: Circling the Bases - Level 1
16. Have students determine the area of the infield drawn previously.
17. Review that 90’x 90’ = 8100’²
18. Provide each student with a copy of the “World’s Biggest Fan” worksheet (included)
and have students work independently to find the area and perimeter of each
shape.
Conclusion:
To conclude this lesson and check for understanding, review each worksheet answer as
a class. Then have each student answer the following questions independently on their
own paper. “What is the difference in length between the longest and shortest
perimeters on the worksheet? What is the difference in area between the smallest and
largest rectangles on the worksheet? Explain the processes you used to get both
answers.”
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Geometry: Circling the Bases - Level 1
Shape & Angle Review
Defining Shapes & Angles
Using the baseball field below, locate the following shapes and angles:
1.
2.
3.
4.
5.
6.
Square
Rectangle
Circle
Diamond
Triangle
Right Angle
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Geometry: Circling the Bases - Level 1
World’s Biggest Fan
Name: __________________
Date: ______________
Instructions: You want your bedroom at home to show that you’re a HUGE
baseball fan. Figure out the perimeter and area of each of the following posters.
Show your work alongside each problem, or on a separate sheet of paper.
1.
20”
10”
20”
Perimeter: _______________
2.
6”
10”
10”
3.5”
3.5”
Perimeter: _______________
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3.
9.5”
12”
12”
9.5”
Perimeter: _______________
Area: _________________
4.
12”
12”
12”
12”
Perimeter: _______________
Area: _________________
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5.
8”
32”
32”
8”
Perimeter: _______________
Area: _________________
6.
5”
4”
4”
5”
Perimeter: _______________
Area: _________________
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Geometry: Circling the Bases - Level 1
World’s Biggest Fan – Answer Key
1. Perimeter: 50”
2. Perimeter: 33”
3. Perimeter: 43”, Area: 114” 2
4. Perimeter: 48”, Area: 144” 2
5. Perimeter: 80”, Area: 256” 2
6. Perimeter: 18”, Area: 20” 2
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