Step Two: Modeling Radius and Circumference
Once students are standing in their group circles, each group will send one member to the middle of the circle with a pre-measured rope. Assist students in stretching the rope from the person in the center to one of the group members on the outer edge of the circle, representing the radius.
While holding the rope, the student on the outer edge will walk around the circle, using chalk to draw the circle’s circumference. Once the circle is drawn, students will lay the rope down on the ground. Have your students use chalk to draw a line from the center of the circle to the outer edge (using the rope as a guide). After drawing the radius, students will measure the radius using yardsticks, measuring tape or rulers, writing the measurement down along the radius.
Ask students to then measure the circumference of the circles by laying the longer jump ropes along the outer edge of the circles, and picking those jump ropes up and using their yardsticks (or similar measuring tools) to measure the length of the rope used to find the circumference of the circles. Students will note the measurement of the circumference along the outer edge of the circle in chalk.
Walk around and collect data from each group, noting the radius and circumference of each circle. After all data has been collected, return to the classroom.