• Give each student (or small group of students) a circular flat object and a flexible measuring tape.
• Have the students measure the distance around (circumference) and the distance across (diameter) the object.
• Open the spreadsheet and display it on the television or with a data projector so the whole class can see.
• Next, each member should report their measurements which are to be entered into their corresponding green and orange cell in the spreadsheeet.
• The ratio of circumference to diameter for each entry will appear in the yellow cell.
• A class average will appear in the purple cell.
• Ask the students what conclusions they can draw about this ratio. Emphasize that all the circular objects are different sizes, but still the ratios are similar.
• When all done, you can formally discuss "pi" and check the second sheet to see how close they are to the actual ratio of "pi".

Standards (Ohio Academic Content Standards):

• Math - Grade 5 - Geometry and Spatial Sense
  • #1 - Draw circles, and identify and determine relationships among the radius, diameter, center and circumference; e.g., radius is half the diameter, the ratio of the circumference of a circle to its diameter is an approximation of pi.
• Math - Grade 6 - Measurement
  • # 2 - Use strategies to develop formulas for finding circumference and area of circles, and to determine the area of sectors; e.g., 1/2 circle, 2/3 circle, 1/3 circle, 1/4 circle.
  • # 3 - Estimate perimeter or circumference and area for circles, triangles and quadrilaterals, and surface area and volume for prisms and cylinders by:
    a. estimating lengths using string or links, areas using tiles or grid, and volumes using cubes;
    b. measuring attributes (diameter, side lengths, or heights) and using established formulas for circles, triangles, rectangles, parallelograms and rectangular prisms.