Obtain some gold plated video cables from your AV department. Have the kids explain why gold is so desirable for high quality video and audio connections. They will almost certainly come up with the idea that gold is a fabulous conductor of electricity so you get more signal. Nope. Actually, a little research will show that gold is 33% MORE resistive to current than typical copper! So why use it if it has MORE resistance? It will not react with air to tarnish and eventually interfere with the signal its carrying. Gold is very chemically inactive, so it will remain a "good" conductor for almost ever.