Gas Math

Gasoline Prices
http://www.gaspricewatch.com/new/
Get your child involved in scouting out cheap gasoline with this web site. They can type their zip code and the distance you're willing to travel ("radius" - use a map and a compass to explain how the term "radius" is the same one they've learned for the distance from the center of the circle to the outside) and get a list of stations with the lowest prices in your area. If there are savings a few miles away, have your child figure out how much you'd save on a whole tank by paying, say, five cents less per gallon. Figure out how much gas you'd use to drive to the far station, and whether or not you'd actually save enough to make it worth the trip.