Learning Design for: Circle
Context
Topic: Circumference of a Circle
Total learning time: 120
Number of students: 25
Description: One hour lesson to acquire: the concept of Circumference; how to find the
Circumference of a circle
Aims
Acquiring the concept of Circle, Diameter, Radius and Circumference Learn to calculate the
Circumference of a Circle
Outcomes
Define(Knowledge): Circle, Diameter, Radius and Circumference
Calculate(Application): Circumference
Derive(Synthesis): Radius from Diameter and viceversa Diameter from Circumference and
viceversa
Teaching-Learning activities
Polygon versus Circle
Discuss
10 minutes
25 students
Tutor is available
What is a polygon? Are all 2D shapes polygons? How would you define a Circle? How can we
compare two circles? What distance/measurements we might need to compare two circles?
Read Watch Listen
5 minutes
25 students
Tutor is available
Teacher illustrates students the following investigative task and explains why is the diameter
of a circle.
Investigate
30 minutes
25 students
Tutor is available
Students will draw three different sized circles. Measure their diameters. Measure, wth the
help of a string, their circumferences. Divide the circumference of each circle by its diameter.
Discuss
15 minutes
25 students
Tutor is available
What did you find out in the previous task? What differences and similarities? How many
times aprroximately can the diameter go around a circumference? (Pi times, 3.14, 22/7)
Radius, Diameter and Circumference Relations
Read Watch Listen
10 minutes
25 students
Tutor is available
From the previous lesson we have learned that the diameter can go around the
circumference of its circle 3 times and a bit, approximately 3.14 or 22/7. We call this ratio of
a circle's circumference to its diameter, pi (π), the Greek letter π. Circumference is equal to π
times diameter.
Practice
30 minutes
25 students
Tutor is available
Solve the following word problems: 1) The diameter of a cent is 16.25 mm. What is the
circumference? 2) The diameter of 2 cents is 18.75 mm. What is the circumference? 3) The
diameter of a compact disc is 9 cm. What is the radius? 4) The diameter of a bicycle wheel is
63,5 cm. How far will you move in one turn of your wheel? 5) Alice buys a round dinner
table. The diameter of dinner table is 12 meters. What is the circumference of table? 6) Paul
purchases a bowl. The diameter of the bowl is 14 cm. What is the circumference of the
bowl? 7) Patricia wants to buy a round photo frame for her brother. The diameter of the
photo frame is 18 cm. What is the photo frame’s circumference? 8) Andrew made a tasty
burger. The diameter of the burger was 5 cm. What was the circumference of the burger? 9)
Michael wants to buy cookies for his friend. The diameter of a cookie is 10 cm. What is the
cookie’s circumference? 10) If the diameter of a circle is 142.8 mm, then what is the circle's
circumference?
Discuss
5 minutes
25 students
Tutor is available
Diameter of a circle is twice of its radius. So if you know a circle’s diameter, you can divide it
by 2 to find the radius; this also means that if you know a circle’s radius, you can multiply it
by 2 to find the diameter. And if you know the Circumference of a circle could you find out
its diameter?
Practice
15 minutes
25 students
Tutor is available
Word Problems 1) The earth average diameter is 12,742 km. What is the its average radius?
2) Mr. Green's pizza shop offers three sizes of pizza. The small, medium and large pizzas have
radii of 4 cm, 5 cm and 6 cm: a) What is the diameter of each size of pizza? b) What is the
circumference of each size of pizza? 3) A Ferris wheel has a radius of 19,812 m. What is the
circumference of the circle? (The circumference is the distance traveled by a passenger in
one full rotation of the Ferris wheel)