1. ?l=0&ID1=AB.MATH.JR.SHAP&ID2=AB.MATH.JR.SHAP.CIRC&lesson=html/
Circles (Unit 8)
Video – Learn Alberta
?l=0&ID1=AB.MATH.JR.SHAP&ID2=AB.MATH.JR.SHAP.CIRC&lesson=html/
video_interactives/circles/circlesSmall.html

2. Construct Circles (Unit 8)
Use your compass to draw a circle…Use a ruler to find your radius first!
Radius
Distance from the centre of the circle to the outside edge…represented by “r”
Diameter
Distance across a circle through its centre…represented by “d”

3. Construct Circles (Unit 8)
Question…
How can you find the diameter if you are given the radius?
d = r x 2

4. Construct Circles (Unit 8)
Question…
How can you find the radius if you are given the diameter?
r = d ÷ 2

5. Let’s Construct Circles
Can you design the Olympic rings using a compass??

6. Practice (Homework) Page 271: # 5ab, 6ab, 7ac, 8c, 10, 14 (Good Luck)
Complete questions on pages…
Page 271:
# 5ab, 6ab, 7ac, 8c, 10, 14 (Good Luck)
Extend #14, 15

7. Circumference of a Circle
Circumference: is the distance (perimeter) around a circle.
Steps:
Wrap a piece of string around the objects circumference...then cut it!
Then measure the string along the side of a metre stick.
Then measure the diameter of your object and relate it to the circumference.
Find The Circumference of Objects!
Circular Object
Circumference
Diameter
How many diameters fit?
Create an equation using “d”

8. Circumference of a Circle
Circumference: is the distance (perimeter) around a circle.
The “∏” is known as pie and is known as 3.14
Diameter
Roughly 3 “d” equal “c”
(3d = c)
Circumference
Actual Equation
(∏d = c)

9. Circumference of a Circle
Circumference: is the distance (perimeter) around a circle.
The “∏” is known as pie and is known as 3.14
Diameter
Roughly 3 “d” equal “c”
(3d = c)
Circumference
Actual Equation
(∏d = c) 5 12 35

10. Circumference of a Circle
Did you KNOW?
The traditional Plains Indian powwow is an annual
celebration. People gather together for storytelling, singing,
dancing and feasting. The powwow grounds are circles and
the performers dance around the circle in a clockwise
direction. How would you determine the distance a dancer
travels in one complete trip around the circle?

11. Circumference of a Circle
PROBLEM:
What if you were given the “radius.” Then how would you find
the circumference? (Remember...before we multiplied the diameter by 3)
The “∏” is known as pie and is known as 3.14
Radius
Your Equation
( )
Circumference
Actual Equation 2 7 12

12. Practice (Homework) # 3ab, 6, 7ab, 10, 11, 17 (Good Luck)
Complete questions on pages…
Page :
# 3ab, 6, 7ab, 10, 11, 17 (Good Luck)
Extend #16, 18, 19

13. Practical Quiz #1
Using a compass, design a 3 level (snowball) snowman.
One snowball has a Diameter of 6 cm
One snowball has a radius of 2 cm
One snowball has a diameter of 3 cm

14. Area of a Circle
Area means the total amount of space inside of a circle (or any shape).
Try to come up with an equation for a circle using the hints given...
What are the hints?
5 m

15. Area of a Circle
Area Equation is…
Answer is…there are roughly 3 squares (l x w) that fit into a circles. The remaining area outside of the circles roughly make up the area in the 4th part of the circle.
Actual Area Equation:
Area = ∏r ²
5 m

16. Area of a Circle
Show all your work...complete one step at a time!
Radius
Estimate Area
A =3 x r x r or A = 3r²
Actual Area
A = ∏r²
6 cm
8 cm
14 cm

17. Area of a Circle
Show all your work...complete one step at a time!
Diameter
Find the “__________”
Estimate Area
(3 x r x r)
Actual Area
(∏r²)
6 cm
10 cm
13 cm

18. Practice (Homework) # 4ab, 6, 9ab, 11, 15, 19 (Good Luck!)
Complete questions on pages…
Page :
# 4ab, 6, 9ab, 11, 15, 19 (Good Luck!)
Extend # 18, 19, 20

19. Create a tattoo based on a circle(s)
Tattoo Me
Create a tattoo based on a circle(s)

20. Create a tattoo based on a circle(s)
Tattoo Me
Create a tattoo based on a circle(s)

21. Create art work based on a circle(s)
Tatoo Me
Create art work based on a circle(s)

22. What is a “Circle Graph”
a graph that
represents data using
sections of a circle
Sector:
a section of a circle
formed by two radii
and the arc of the
edge of a circle, which
connect the radii

23. Interpret Circle Graphs
What is the graph about?
What do the different sectors represent?
What percent does Mrs. Bosch run?
What percent does Mr. Kittie and Mr. Bosch represent?
What do all the sectors add up to be (percent wise)?

24. Interpret Circle Graphs
What is the graph about?
What do the different sectors represent?
If you have a cat?
What are your chances of being a smart kid?
What are Mr. Bosch’s chances of being a smart kid?

25. Practice (Homework) # 3, 5, 7, and 8 Page 290-291:
Complete questions on pages…
Page :
# 3, 5, 7, and 8

26. Create Circle Graphs You will need…
Ruler Protractor Compass Pencil Crayons
Construct a circle graph with a radius of 8 cm.
Create the circle
Questions:
How many degrees are in the top ½ of the circle?
How many degrees are in the bottom ½ of the circle?
What is the sum of the central angles of a circle?
8 cm

27. Create Circle Graphs Complete a Class Survey on Types of Pets!
You can only select ONE of the animals mentioned above.
Then complete the chart above as a class and work
with a partner to create your “Circle Graph.”
Favourite House Pet
Cat
Dog
Bird
Fish
Other
Number of Students
Fraction
Percent
Percent of 360°

28. Create Circle Graphs % of 360° decimal x 360° Example: 45% x 360°
How do we find the “degrees” of something?
% of 360° decimal x 360°
Example: 45% x 360°
0.45 x 360° = 162°

29. Results of Class Survey on Types of Pets!
Create Circle Graphs
Results of Class Survey on Types of Pets!
Cat ( %)
Dog ( %)
Bird ( %)
Fish ( %)
Other ( %)

30. Create Circle Graphs Create your OWN survey! (must have 5 choices) ???
Once you’ve completed your data then complete circle
graph…make sure to have a LEGEND! Make sure the people
you survey only select ONE of the choices!
???
Number of Students
Fraction
Percent
Percent of 360°

31. Unit Review Page 298-299: # 8a, 9b, 12ad, 13, 14, 18, 20
See the “JEOPARDY” game in the Math 7 File…
Unit Review Questions:
Page :
# 8a, 9b, 12ad, 13, 14, 18, 20