1. Materials Needed: Directions:
Styrofoam ball, scissors, tape, paper
Directions:
Cut the ball along the great circle.
Trace around the hemisphere on the paper.
What is the term for this figure?
3. Cut out the great circle.
4. Fold the circle into eighths
(fold in ½ 3 times).
5. Unfold the circle.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia

2. 6. Cut the following folds.
7. Tape the pieces together as shown.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia

3. ¼ πr2 Questions: 8. Use the pins to attach the pattern to the ball.
Approximately how much of the total surface of the sphere is covered by the pattern?
What is the area of the great circle in terms of r and π?
Questions:
πr2
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia

4. 4 4πr2 2. How many great circles would it take to cover the sphere?
3. What is the formula for the surface area of a sphere? 4
4πr2
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia

5. **You can use the plastic playground balls and masking tape instead of the Styrofoam ball and pins. My plastic balls have a 3” diameter. The students trace and cut out the great circle using a solo cup with a 3” diameter.
© 2009, Dr. Jennifer L. Bell, LaGrange High School, LaGrange, Georgia