Clicking on an athlete adds or removes them from the list of observers. Pressing the space key makes all athletes in the observer list perform their action, demonstrating dynamic behavior based on their subscription status.
This Scratch project demonstrates the Observer design pattern by allowing athlete sprites to subscribe or unsubscribe from an event. When the space key is pressed, only the subscribed athletes change their costume to perform their action, showcasing how observers respond to changes in the subject's state.