Circles (Unit 8)

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Circles (Unit 8). AC DR Area Circumference Diameter Radius. Circles (Unit 8). Video – Learn Alberta. http://www.learnalberta.ca/content/mejhm/index.html ?l=0&amp;ID1=AB.MATH.JR.SHAP&amp;ID2=AB.MATH.JR.SHAP.CIRC&amp;lesson=html/ video_interactives/circles/circlesSmall.html.

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AC DR

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

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

Let’s Construct Circles

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

Let’s Construct Circles

• 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

Practice (Homework)

• 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

Practical Quiz # 1

• 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

Practice (Homework)

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

Practical Quiz #2

• 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!

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

Practice (Homework)

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

Practical Quiz # 3

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

Tattoo Me

• Create a tattoo based on a circle(s)

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

Tattoo Me

• Create a tattoo based on a circle(s)

RUBRIC

Circumference /1

Diameter /1

Area /1

Colored /3

Neatness /3

Originality /3

TOTAL /13

Tattoo Me

• Create a tattoo based on a circle(s)

Tatoo Me

• 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
• and the arc of the
• edge of a circle, which

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

Interpret Circle Graphs

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)?

Interpret Circle Graphs

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?

Practice (Homework)

• 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!

Unit Review

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