Circumference is the distance around something. A tape measure is used to measure circumference. The unit for circumference is centimeters. The abbreviation is cm. 1. Take a picture of your rock. 2. Use the tape measure to measure the widest circumference of your rock. Be sure to start at 0. 3. Use the red tool to draw a line where the widest circumference is. 4. Use the label tool to label the circumference. Include the correct unit (cm). 5. Record a summary of this activity. Be sure to use circumference, tape measure, and centimeters.