Pi in your face!! Cottonwood CA 96022
Standards
Introduction
Students will investigate several circular objects in order to understand the meaning of pi and solidify the formulas of a circle.
Subject: Math
Topic: Geometry and Measurements of a circle
Student Lesson name and URL: Pi in your face
Math Measurement and Geometry
•  1.0 Students deepen their understanding of the measurement of plane and solid shapes and use this understanding to  solve problems:
• 1.1 Understand the concept of a constant such as p; know the formulas for the circumference and area of a circle.
• 1.2 Know common estimates of p(3.14; 22/7) and use these values to estimate and calculate the circumference and the area of circles; compare with actual measurements.
Standards
Instructional Objectives
1.  Students will understand the vocabulary of a circle: center, diameter, radius, chord, arc, circumference, and pi
2. Student measure circumference to nearest millimeter.
3. Students will compare the area of each object found.
4. After given one measurement students will be able to find the circumference and area.
5. Students will use a spreadsheet to organize measurements of 5 round objects. Suggestions are soup cans, soda containers, basketball count, garbage cans, tape rolls, ect...
Student Activities -Go Here for Student Work
Students will take a pretest, and list daily occurrences of circles.
Pretest
Introductory Activity
What do you know about circles? (Pretest)
In teams of 2-3, list all the places you might see a circle today.
Day 1 - Vocabulary Students will make a game, crossword puzzle, word search or other activity for the following words:center, diameter, radius, chord, arc, circumference,  pi, area, central angle
Day 2 - Switch It- Students give their work to someone else  to do. This is the review.
Materials Needed: various round objects, string, and ruler. Have students make a spreadsheet or graph as shown here.
At least five objects will be used. Measure to the nearest millimeter
Enabling Activities
Collect several objects the students listed. Set up a spreadsheet or have student make one.
 Object Circumference Diameter Ratio: Circumference/Diameter 1. 2. 3. 4. 5.

What is the value for the ratio? Pi =3.14(159..)
Day 3    Review - Take the students out to the basketball courts.  Each team of 4-5 students need one circle. Ask them to show in the circle circumference, diameter, radius, arc and area.
Activity - Materials: Graph paper, soda can, transperancy graph
Area- It won't fit on graph paper!  Circles don't fit nicely on graph paper. On the overhead  trace the bottom of a soda can. Place graph transperency of it.  Can you figure out how many square centimeters there are.  What are some of the problems you run into?  Discuss There is a formula for the area of a circle.  Area = ? * r * r.  Let's do it as a class.  Write the examples and answers down If the radius is 5, find the Area. Do on overhead. Check. Give the following radii and diameters.  Check progress and then review as class R = 6,  R= 3, R = 7   D= 8, D= 10, D =4, *D =7
What are the formulas we use for a circle?
C=d*3.14 Or C=2(r)(22/7)    A = 22/7(r)(r)
Pi can be 3.14 or 22/7 it depends on how accurate you need to be.

Assessment

3 Station Test.
Culminating Activity
3 Station test.
Station One - Show these definitons and illustrate them: center, diameter, radius, chord, arc, circumference,  pi, area, central angle
Station Two - Show the steps to find the Area of a circle if the diameter is 8, and another if the radius is 5.
Station Three -Show the steps to find the Circumference of a circle if the diameter is 10, and another if the radius is 3.

Results

Web Resources & Supplementary Materials

Introductory Activity
http://www.gomath.com/htdocs/lesson/circle_lesson1.htm

Enabling Activity
There is a great AIMS activity called Magic Circle. Here is the AIMS web site  http://www.aimsedu.org/

Culminating Activity
http://www.gomath.com/geometry/circle.asp

School Name Evergreen Union School District
School Location Cottonwood CA
Denise Evans deevans@eusd.tehama.k12.ca.us
Last Revised: 1/18/2001