Participation criterion is the rule that grown-ups use to decide who can play a game or take part in an activity. Imagine you want to play a game with your friends. Your mom or dad might say, "Okay, you can play, but you have to follow the rules and play nicely with your friends." That's the participation criterion! It means that if you follow the rules and play nice, you can be part of the game or activity.
Just like games, there are other activities that have their own participation criterion. For example, if you want to be part of a school sports team, the coach might say that you have to practice every day, show up on time, and work hard to improve your skills. If you can do those things, you get to be part of the team and play in games against other schools.
Participation criterion is a way for grown-ups to make sure that everyone who takes part in something is doing their best and being helpful to others. It's important to follow the participation criterion so that everyone can have fun, be safe, and have a good time doing whatever they are doing!