Just press a hidden button on one, and it emitted some chiming notes. Then press the button on the other egg and it will chime as well. Then it make electronic chirping sounds. The one egg makes an intermittent noise until it is jostled; then it goes silent and then the other egg will make a noise. You put the eggs around 20-30 feet apart and then your dog will quickly figure out how they work and will have fun running from one to the other.