Before the meeting: 

1. Print the Pendulum Experiment worksheet for each Cub Scout or use the Webelos handbook. 
2. Use the tutorial video on the Yo-Yo Preview Adventure website and How to be a Yo-Yo Ninja: Getting Started (1:36 minutes) for assistance with the requirements. 
3. Set up area for Cub Scouts to fill out worksheet. 

During the meeting: 

1. Explain to Cub Scouts that it is important to have the correct string length for their yo-yo. They will be conducting an experiment to show how the wrong length can impact the yo-yo performance. 
2. Hand out the Pendulum Experiment worksheet or have them open their handbook to the correct page.  
3. Complete the first experiment: 
   • Ask the Cub Scouts to hold the string about 12-inches up from the yo-yo and gently swing it from side to side. 
   • Explain that a pendulum can accurately measure time, and the amount of time the yo-yo takes to swing from left to right and back again is known as a period. 
   • Next, have the Cub Scouts return to gently swinging the yo-yos from side to side, but this time, have the Cub Scouts hold the string farther from the yo-yo or closer to it. 
   • Ask the Cub Scouts who held the string farther from the yo-yo what happened. (The result should be a longer period.) 
   • Ask the Cub Scouts who held the string closer to the yo-yo what happened. (The result should be a shorter period.) 
4. Have Cub Scouts fill out their Pendulum Experiment worksheet. 
5. Conduct the second experiment: 
   • Suspend the yo-yo about 12-inches from the yo-yo. 
   • Lift the yo-yo up and to the same height as the anchor point. 
   • Release the yo-yo. 
   • Use a stopwatch to record the number of seconds it takes the yo-yo to swing from the release side and back to the release side, 10 times. 
   • Divide the number of seconds by 10. This is the pendulum’s period in seconds. 
   • Suspend the yo-yo about 6-inches from the yo-yo. 
   • Lift the yo-yo up and to the same height as the anchor point. 
   • Release the yo-yo. 
   • Use a stopwatch to record the number of seconds it takes the yo-yo to swing from the release side and back to the release side, 10 times. 
   • Divide the number of seconds by 10. This is the pendulum’s period in seconds. 
   • Ask the Cub Scouts what happened when the string is longer. (The result should be a longer period.) 
   • Ask the Cub Scouts what happened when the string is shorter. (The result should be a shorter period.)