Be certain the students use a flat object as this will reflect the Motion Sensor's ultrasonic waves back to the sensor best.

If your Motion Sensors have a switch, be sure it is set to cart (near).

Emphasize that power is the change in energy per unit time and this can involve any energy changes, not just gravitational energy.

To download the Power of Energy DataStudio file with sample data for this experiment, click on a Windows (Zip file) or Macintosh (Stuffit file).