Circles (Unit 8)

1. 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

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) • 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!

8. Circumference of a Circle • Circumference: is the distance (perimeter) around a circle. • The “∏” is known as pie and is known as 3.14 http://www.learnalberta.ca/content/memg/index.html?term=Division03/Circumference/index.html

9. Circumference of a Circle • Circumference: is the distance (perimeter) around a circle. • The “∏” is known as pie and is known as 3.14

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

12. Practice (Homework) • Complete questions on pages… • Page 278-279: • # 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. 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

15. 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

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

17. Show all your work...complete one step at a time! Area of a Circle

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

19. Tattoo Me • Create a tattoo based on a circle(s) http://www.arcvillage.org/KIDSTUFF/crop%20circle%20designs.htm

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

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

22. What is 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

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) • Complete questions on pages… • Page 290-291: • # 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.”

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

29. 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!

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