LESSON
PLAN IN MATH
I. OBJECTIVES
A. Discover
the formula for finding circumference using pi and diameter
B. Solve
problems involving circumference of a circle
C. Work
cooperatively in groups
II. SUBJECT MATTER
A.
Circumference of a Circle
B. BEC
PELC Math V 1; 1.1; 2; 2.1.11.4
C.
pictures, circular/round objects, string, ruler, activity sheets
D.
Cooperation
III. Procedure
A. Preparatory Activities
1. Review
Who is the Father of Geometry? Find
the perimeter of the following plane figures/polygons to find out.(Draw your figure beside the numbers.)
1. 2. 3.
4. 5. 6.
______ _____
_____ _____ _____
_____
3 1 5 4 2 6
2. Motivation
Ask: How well are you familiar with different
circles around you? Identify the following circular objects shown in the
following pictures.
·
Show
pictures of circular objects and let pupils raise their hand if they know the
object.
Ask: Do you know that circles just like polygons
also have perimeter? How do we call the perimeter of a circle? How do we solve
for the distance around the circle?
B. Developmental Activities
1. Presentation
Group Activity: Exploration with
Discs
·
Divide
Pupils into 5 groups and let them gather in circle.
·
Orient
the pupils on the rules and proper decorum during group activity.
·
Distribute
the needed materials and activity sheets. Instruct pupils to read carefully the
directions.
·
Emphasize
the importance of cooperation to successfully accomplish the task.
·
Guide
pupils while the activity is going on. Have them focus on the following
questions:
a.
What is the distance/length around
the circular object?
b.
What is the distance/length across
the circular object?
c.
What is the value if we will divide
the length around the circular object by the length of the circular object?
Express your answer to the nearest hundredth.
·
Let
pupils write their results in the matrix written in the chalkboard. Have them
observe and compare their result with the result of the other groups.
Ask: What have you noticed with your results? Are
the results similar? Why do you think are they similar?
·
Introduce
that the distance/length around the circular object is called the CIRCUMFERENCE.
Relate that the CIRCUMFERENCE is actually the “PERIMETER” of a circle. The
distance across the circular object is called the DIAMETER. Half the diameter
is called the RADIUS.
·
Elaborate
that long time ago, people started to notice that the Circumference of a circle
is approximately 3 times the diameter. Discuss that at present, mathematicians
have accurately solved this value to 3.1415926535 or simply 3.14. This value is
called as pi (π).
·
Present
the equation to the class: π = . Explain that if this equation would be rearranged, we can have
C= π x d. Since the radius is half the diameter, circumference can also be
solved through C= π x 2 x r.
·
Let
pupils memorize the formula in finding the circumference through body movements.
Provide
the following example:
Liza
wants to put a lace around a circular pillow. If the pillow has a diameter of
20 dm, how long should be the lace?
Let
pupils analyze the problem using STAR Strategy.
ü SSearch
the Problem
The
circular pillow has 20 dm diameter.
I need to
use pi which is equal to 3.14.
I need to
find the circumference of the pillow to find the length of the lace.
Or
simply, d= 20; pi= 3.14 C= ?
ü TTranslate
the problem into an equation
C= π x
d C=3.14 x 20 dm
ü AAnswer
the Problem
C=3.14 x
20 dm
C= 62.8
dm The length of the lace needed is
62.8 dm.
ü RReview
the Solution
Since π =
C/d, hence 62.8 dm/20 dm should be equal to 3.14.
62.8
dm/20 dm = 3.14
3.14=3.14
Provide
other examples:
a. A circular fountain has a diameter of 4 m.
What is the circumference of the fountain?
b. A circular aviary needs to be surrounded
with screen. If the aviary measures 15
ft across, how long should be the screen needed to surround the aviary?
2. Fixing Exercises (PairShare
Activity)
Find
the circumference. Use pi=3.14
1. 2.
3. What is the circumference of a circle with a
diameter of 4.5 cm?
4. A round wooden table has a radius of 2 m. Find its circumference.
5. Give the circumference of a clock with 9 inches
as its diameter.
3. Generalization
·
What is the circumference of a
circle?
·
What is pi? What is the value of pi?
·
How do we solve for the circumference
of a circle?
C. Application
Imagine
you’re the person in the following problems then give your solution.
1. You are a gardener. A round flower plot needs to be fenced with wire. If it measures 9 m across, how long should be
the wire needed to fence around the plot?
2. The distance around a circular running field
is 75 m. If you are a runner and you want to run across the field, how far
would your run be?
IV. Evaluation
Read the
problem and show you solution.
1.
2.
3. Give the circumference of a circle with 3.5
cm as its radius.
4. What is the diameter of a round mirror if
its circumference is 35 dm?
5. A rubber tire measures 3 ft across. Find its
circumference.
V. Assignment
Try to
look for round/circular objects around your house. Then complete the table
below.
Object

Diameter

Radius

Circumference

e.g.
plate




















Prepared by:
JAYLORD S. LOSABIA
Teacher I
A. Bonifacio Elementary
School
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