Today a child brought in a small wind up music box. X accidentally discovered that when he put it on the picnic table the sound became louder. I said sound waves travelling through the bench make the sound louder, in response. He then had the idea of putting it on the pavier bricks. Asking him which material sound waves travel through better, X replied "wood because it is louder." Asking him what other materials he could find X said "plastic... the slide." Testing it I asked which the sound waves travelled through best now? X correctly ordered them as wood, plastic then brick. I asked if he could see anything else to test it on. X said metal and went over to the fence. He immediately declared that was the loudest.