circles (unit 8) video – learn alberta ...

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

circumferenceUse your compass to draw a circle…Use a ruler to find your radius first!

RadiusDistance from the centre of the circle to the outside edge…represented by “r”

DiameterDistance 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 CircleStudent outcome: I will be able to describe the relationship of radius, diameter and

circumference

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

Steps:1. Wrap a piece of string around the objects circumference2. Then measure the string along the side of a metre stick.3. Then measure the diameter of your object and relate it to the circumference.

Find The Circumference of Objects!

Circumference of a CircleStudent outcome: I will understand radius, diameter, circumference relationships.

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

Circular Object

Circumference Diameter How many diameters can you

fit around the circumference

(estimated)

Create an equation using “d”

Find The Circumference of Objects!

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

Circumference of a CircleStudent outcome: I will understand radius, diameter, circumference relationships.

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

C = 3 x d (estimated)

C = ∏ x d (actual)

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

∏ is very close to 3 (friendly number)

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

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

Circumference of a CircleStudent 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

DiameterEstimated

CircumferenceC= 3 x d

Actual Circumference

C= ∏ x d

5127

Circumference of a CircleStudent outcome: I will understand radius, diameter, circumference relationships

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

DiameterEstimated

CircumferenceC= 3 x d

92133

Circumference of a CircleStudent 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

DiameterActual

CircumferenceC= ∏ x d

21.98

370.52

703.36

Practical Quiz # 1

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

DiameterEstimated

CircumferenceC = 3 x d

Actualcircumference

C = ∏x d

10

3

15

Circumference of a CircleDid you KNOW?

The traditional Plains Indian powwow is an annualcelebration. People gather together for storytelling, singing,dancing and feasting. The powwow grounds are circles andthe performers dance around the circle in a clockwisedirection. How would you determine the distance a dancertravels in one complete trip around the circle?

Circumference of a CircleStudent outcome: I will understand radius, diameter, circumference relationships

PROBLEM:What if you were given the “radius.” Then how would you findthe circumference? (Remember...before we multiplied the diameter by

3)

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

Radius(r) r + r = d

Estimated Circumference

C = 3 x d

Actual Circumference

C = ∏x d

27

12

Practice (Homework)Complete questions on pages…

Page 278-279:

# 3ab, 6, 7ab, 10, 11, 17 (Good Luck)

Extend #16, 18, 19

Practical Quiz #2Using a compass, design a 3 level (snowball) snowman.

One snowball has a radius of 2 cmOne snowball has a radius of 3 cmOne snowball has a diameter of 2 cm

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

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

Area of a Circle

Radius Estimate Area A = 3 x r x r or A = 3r²

Actual AreaA = ∏r² or A = ∏ x r x r

6 cm

8 cm

14 cm

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

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

Diameter Find the “_________”

Estimate AreaA = 3r² or A = 3xrxr

Actual AreaA= ∏r² or A = ∏xrxr

6 cm

10 cm

13 cm

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

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

DiameterActual

circumferenceC = ∏x d

10

3

18.84

Tattoo MeCreate a tattoo based on a circle(s)

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

Tattoo MeCreate a tattoo based on a circle(s)

RUBRIC

Circumference /1Diameter /1Radius /1Area /1

Colored /3Neatness /3Originality /3

TOTAL /13

Tattoo MeCreate a tattoo based on a circle(s)

Tatoo MeCreate art work based on a circle(s)

What is a “Circle Graph”Student outcome: I will be able to read a circle graph.

Sector:

a section of a circleformed by two radiiand the arc of theedge of a circle, whichconnect the radii

Circle Graph: a graph thatrepresents data using sections of a circle

Who Runs The Show?

WifeKidsMe

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

Interpret Circle GraphsStudent outcome: I will be able to read a circle graph.

50%35%

15%

Who Runs The Show?

Wife Kids

Me

1. What is the graph about?

2. What do the different sectors represent?

3. What percent does Mrs. Bosch run?

4. What percent do the kids and Mr. Bosch represent?

5. What do all the sectors add up to be (percent wise)?

Interpret Circle GraphsStudent outcome: I will be able to read a circle graph.

1. What is the graph about?

2. What do the different sectors represent?

3. If you have a cat?

4. What are your chances of being a smart kid?

5. What are Mr. Bosch’s chances of being a smart kid?

20

25

1015

20

10

Smarter Kids Have?Brown Hair

A Frog

A Sister

A Truck

Blue Eyes

A Spouse

Practice (Homework)Complete questions on pages…

Page 290-291:

# 3, 5, 7, and 8

Create Circle GraphsStudent 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.

1. Create the circle

Questions:a) How many degrees are in the top ½ of the circle?b) How many degrees are in the bottom ½ of the circle?c) What is the sum of the central angles of a circle?

8 cm

Create Circle GraphsStudent 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.”

Favourite House Pet

Cat Dog Bird Fish Other

Number of StudentsFraction

Percent

Percent of 360°

Create Circle GraphsStudent 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 GraphsStudent 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 GraphsStudent 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!

Question

Number of StudentsFraction

Percent

Percent of 360°

Unit ReviewSee the “JEOPARDY” game in the Math 7 File…

Unit Review Questions:

Page 298-299:

All questions except #10, 22