Circles (Unit 8)

AC DR Area Circumference Diameter Radius

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

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

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 RingsRubric – Olympic rings 5 exact rings/55 exact rings/5 Parallel/2Parallel/2 Straight Lines/3Straight Lines/3 Spacing /Overlap/3Spacing/Overlap/3 Neatness/2Neatness/2 Total/15Total/15

Practice (Homework) Page 271: 5c, 8c, 10, 11, 14 8ab5c, 6c, 7c, 8c, 10, 11 5a, 6, 7, 8b, 10

Circumference of a Circle Student outcome: I will understand radius, diameter, circumference relationships. Circumference: is the distance (perimeter) around a circle. Circular Object CircumferenceDiameterHow 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 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: 1.Wrap a piece of string around the objects circumference 2.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 Circle Student 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) 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 The “∏” is known as pi and is known as 3.14 Diameter Estimated Circumference C= 3 x d Actual Circumference C= ∏ x d

Circumference of a Circle Student outcome: I will understand radius, diameter, circumference relationships Circumference: is the distance (perimeter) around a circle. Diameter Estimated Circumference C= 3 x d

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 Diameter Actual Circumference C= ∏ x d

Show Me What You Know# The “∏” is known as pi and is known as 3.14 Diameter Estimated Circumference C = 3 x d Actual circumference C = ∏x d

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) 3.14 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

Practice (Homework) Page : 2, 15, 16, 18, , 3a, 6, 11, 12, 13 1, 2, 3a, 5, 6, 7a, 9

Secret to the perfect pancake is discovered

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

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 4 th part of the circle. Actual Area Equation: Area = ∏r ² 5 m Area of a Circle