Learn about the physics of resistance in a wire. Change its resistivity, length, and area to see how they affect the wire's resistance. Predict how changing each variable will affect the resistance.
I just purchased crackle subway tile (3x6) for our backsplash. As I was shopping around it seemed that $12-15 per square foot was the average price. You can get cheaper but they were VERY basic. I ended up with a Sonoma tile which was hand molded and cost $20 square foot.
For the backsplash material itself - can run from $10-15/sf for a panel material, $15-25 for stainless steel or copper, $7-25 for tile, $25-50 for real stone, up to $250/sf and more for custom made pattern or designer tile.