Lesson to Teach the Basics of Pi

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Multiple Choice

Pi Day is celebrated on March 14. (which was chosen because it resembles 3.14) What time does the official celebration begin?

• 3:14 PM

• 7:22 PM

• 1:59 PM

• 5:18 PM

What IS pi anyway?

Anciently, mathematicians determined that there was a relationship between the diameter of a circle and its circumference. The distance around a circle was a tad more than 3 times as long as the diameter. π is a constant that is used in formulas related to circles.

Multiple Choice

1.How many digits are in the decimal equivalent of Pi?

• About 6,904,731

• No one really knows

• 6,904

• at least 50 Trillion

Multiple Choice

What is the seventh digit of pi?

• 2

• 4

• 6

• 8

Multiple Choice

What is pi a ratio between?

• Diameter:radius

• Diameter:circumference

• Circumference:radius

• Circumference:diameter

• Radius:circumference

Multiple Choice

$$\pi$$ (Pi) is the 16th letter in which alphabet?

• Greek

• Roman

• Arabic

• Chinese

Multiple Choice

What famous mathematician was born on Pi Day?

• Euler

• Aristotle

• Einstein

• Bill Nye

Happy Birthday, Al!

Multiple Choice

What mathematical formulas depend on pi?

• Area of a circle

• Surface area of a cone

• Surface area of a sphere

• Volume of a cylinder

• All of these

Multiple Choice

What do you get when you divide the circumference of a pumpkin by its diameter?

• A Jack-o-lantern

• Too much mathing

• Smashing Pumpkins

• Pumpkin Pi!

Multiple Choice

A circle is defined as a set of points all _______ from a center point.

• equidistant

• stretched

• scattered

• different distances

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

Multiple Choice

What does the point A represent?

• Radius

• Center

• Diameter

• Origin

Multiple Choice

What is the diameter?

• 5 in
• 10 in
• 3.14 in
• 15.84 in

Multiple Choice

Define "radius"

• A line segment that connects the center to the circumference

• The point in the middle of the circle

• A line segment that passes through the center

• The distance around the circle

Multiple Choice

Define "diameter"

• A line segment that connects the center to the circumference

• The point in the middle of the circle

• A line segment that passes through the center

• The distance around the circle

Multiple Choice

Define "circumference"

• A line segment that connects the center to the circumference

• The point in the middle of the circle

• A line segment that passes through the center

• The distance around the circle

Multiple Choice

What is the "formal" definition of pi?

• 22/7
• 3.1415926
• the ratio of a circle's circumference to its diameter
• the surface area of a sphere of diameter 22/7

Multiple Choice

What is the correct decimal approximation for pi (π)?

• 2.17828

• 6.0223

• 3.14

• 1

Multiple Choice

The diameter of a circle is 20 ft. What is the radius?

• 10 ft

• 62.8 ft

• 5 ft

• 3.14 ft

Multiple Choice

The radius of a circle is 10 ft. What is the diameter?

• 20 ft

• 62.8 ft

• 5 ft

• 3.14 ft

Learning Objectives

• Today, we will determine how to find the circumference and area of a circle

• identify the radius and diameter of a circle

What is Circumference?

Multiple Choice

True or False: The diameter is being pictured here.

• True

• False

Multiple Choice

True or False: The diameter is twice as long as the radius.

• True

• False

Multiple Choice

The diameter of a circle is 10 inches. What is the radius?

• 10 inces

• 20 inches

• 5 inches

• 2.5 inches

Open Ended

The radius of a circle is 12 cm. What is the diameter?

How do I find the circumference using the formula?

Example 1: The diameter of a circle is 12 cm. What is the circumference?

Example 2: The radius of a circle is 5 inches. What is the circumference?

Multiple Choice

Find the circumference. Leave your answer in terms of pi. 

 

• 8 $$\pi$$  

• 4

• 2 $$\pi$$  

• 4 $$\pi$$  

Open Ended

Find the circumference of a circle if the radius is 2.5 inches. Use 3.14 for pi.

Area of a Circle

Example 1: Find the area of a circle if the radius is 8 cm. Leave your answer in terms of pi. 

Example 2: Find the area of a circle if the diameter is 12 inches. Use 3.14 for pi. 

Multiple Choice

Find the area of this circle. Leave your answers in terms of pi. 

• $$25\pi$$

  
  

• $$5\pi$$

• $$10\pi$$

• $$100\pi$$

Multiple Choice

What is the area of this circle? Use 3.14 for pi. 

• 12.56

• 25.12

• 50.24 

• 200.96

Open Ended

Find the area of a circle if the radius is 7 inches. Use 3.14 for pi.

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