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### Area of a CircleStudent outcome: I will be able to solve the area of a circle.

Circles(Unit 8)

Area Circumference Diameter Radius

Circles(Unit 8)

- Video – Learn Alberta

- http://www.learnalberta.ca/content/mejhm/index.html
- ?l=0&ID1=AB.MATH.JR.SHAP&ID2=AB.MATH.JR.SHAP.CIRC&lesson=html/
- video_interactives/circles/circlesSmall.html

Construct Circles(Unit 8)

Student outcome: I will be able to describe the relationship of radius, diameter and circumference

- 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”

Construct Circles(Unit 8)

Student Outcome: I will be able to describe the relationship between radius, diameter and circumference

- Question…
- How can you find the diameter if you are given the radius?

d = r x 2

Construct Circles(Unit 8)

Student Outcome: I will be able to describe the relationship between radius, diameter

- Question…
- How can you find the radius if you are given the diameter?

r = d ÷ 2

- Can you design the Olympic rings using a compass??

- Can you design the Olympic rings using a compass??

Rubric – Olympic Rings Rubric – Olympic rings

5 exact rings /5 5 exact rings /5

Parallel /2 Parallel /2

Straight Lines /3 Straight Lines /3

Spacing /Overlap /3 Spacing/Overlap /3

Neatness /2 Neatness /2

Total /15 Total /15

- Complete questions on pages…
- Page 271:
- # 5ab, 6ab, 7ac, 8c, 10,
- Extend #14, 15

Circumference of a Circle

Student outcome: I will be able to describe the relationship of radius, diameter and circumference

- Circumference: is the distance (perimeter) around a circle.
- Steps:
- Wrap a piece of string around the objects circumference
- 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!

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships.

- Circumference: is the distance (perimeter) around a circle.

Find The Circumference of Objects!

- What is the relationship between the diameter and circumference of a circle?

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships.

- Circumference: is the distance (perimeter) around a circle.

- What is the relationship between the diameter and circumference of a circle?
- ∏ is very close to 3 (friendly number)

C = 3 x d (estimated)

C = ∏ x d (actual)

- The “∏” is known as pi and is known as 3.14

http://www.learnalberta.ca/content/memg/index.html?term=Division03/Circumference/index.html

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships

- Circumference: is the distance (perimeter) around a circle.
- The “∏” is known as pi and is known as 3.14

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships

- Circumference: is the distance (perimeter) around a circle.

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships

- Circumference: is the distance (perimeter) around a circle.
- The “∏” is known as pi and is known as 3.14

- The “∏” is known as pi and is known as 3.14

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?

Circumference of a Circle

Student outcome: I will understand radius, diameter, circumference relationships

- 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 pi and is known as 3.14

- Complete questions on pages…
- Page 278-279:
- # 3ab, 6, 7ab, 10, 11, 17 (Good Luck)
- Extend #16, 18, 19

- Using a compass, design a 3 level (snowball) snowman.
- One snowball has a radius of 2 cm
- One snowball has a radius of 3 cm
- One snowball has a diameter of 3 cm

Areaof 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

Areaof 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

Areaof a Circle

Student outcome: I will be able to solve the area of a circle.

Show all your work...complete one step at a time!

- Complete questions on pages…
- Page 285-286:
- # 4ab, 6, 9ab, 11, 15, 19 (Good Luck!)
- Extend # 18, 20

- The “∏” is known as pi and is known as 3.14

- Create a tattoo based on a circle(s)

http://www.arcvillage.org/KIDSTUFF/crop%20circle%20designs.htm

- Create a tattoo based on a circle(s)

RUBRIC

Circumference /1

Diameter /1

Radius /1

Area /1

Colored /3

Neatness /3

Originality /3

TOTAL /13

- Create a tattoo based on a circle(s)

- Create art work based on a circle(s)

What is a “Circle Graph”

Student outcome: I will be able to read a circle graph.

- 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

http://www.learnalberta.ca/content/memg/index.html?term=Division03/Circle_Graph/index.html

Student outcome: I will be able to read a circle graph.

- What is the graph about?
- What do the different sectors represent?

- What percent does Mrs. Bosch run?
- What percent do the kids and Mr. Bosch represent?
- What do all the sectors add up to be (percent wise)?

Student outcome: I will be able to read a circle graph.

- 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?

- Complete questions on pages…
- Page 290-291:
- # 3, 5, 7, and 8

Create Circle Graphs

Student outcome: I will be able to build a circle graph.

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

8 cm

Create Circle Graphs

Student outcome: I will be able to build a circle graph.

- 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.”

Create Circle Graphs

Student outcome: I will be able to build a circle graph.

- How do we find the “degrees” of something?

- % of 360° decimal x 360°

- Example: 45% x 360°
- 0.45 x 360° = 162°

Create Circle Graphs

Student outcome: I will be able to build a circle graph.

- Results of Class Survey on Types of Pets!

Cat ( %)

Dog ( %)

Bird ( %)

Fish ( %)

Other ( %)

Create Circle Graphs

Student outcome: I will be able to build a circle graph.

- 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!

- See the “JEOPARDY” game in the Math 7 File…
- Unit Review Questions:
- Page 298-299:
- All questions except #10, 22

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