There are seven principles[1] which are reworded as the "leave no trace principles for kids"[2] below in parentheses.
Plan ahead and prepare (Know before you go)
Travel and camp on durable surfaces (Choose the right path)
Dispose of waste properly (Trash your trash)
Leave what you find
Minimize campfire impacts (Be careful with fire)
Respect wildlife
Be considerate of others (Be kind to other visitors)