Have you ever seen a video where it looked like a car's wheels or a helicopter's blades were spinning backwards? This optical illusion is called the wagon wheel effect, named after old movies where it looked like wagon wheels were spinning backwards. This video explains what the wagon wheel effect is and how you can film it yourself at home with a fan or a drill. Written instructions for this fun STEM activity are available on the Science Buddies website: https://www-stage.sciencebuddies.org/stem-activities/wagon-wheel-effect-optical-illusion