I picked oil! The weblink I put at the bottom of this is one to a map of Alaska, with the path of the pipeline indicated on it. I would use this map, and the other information on this website, which says that the oil moves about 5.4 miles per hour. I would ask the students to stand up and jog in place for a moment. The pace they are jogging, is probably somewhere near the 5.4 miles per hour. If they were to jog that fast for 6 days, they too could travel the 800 miles of the pipeline. This would let me start talking about where the oil starts and ends and what you might find along the way, if you were to jog all the way from the top to the bottom of the map.