Flickr

Below is a picture I found in the Flickr Commons

media type="custom" key="20397346"

In 6th grade math, we spend a lot of time calculating unit prices, and this would get us talking about what a unit price is, and how to calculate it. You can see the number of gallons, the total cost, and the unit price can easily be calculated. I could give the students the task of finding out the price per gallon, just given the number of gallons and the total cost.