This is a great worksheet for a math class working on proportional reasoning as well as percentages. I would also recommend this for any health teacher working on nutritional facts. This worksheet may even be good in a science class.
This worksheet will require that each student bring in a snack wrapper labeled with nutritional facts. The rest of the worksheet is self explanatory if the students have worked with proportions and will allow students to investigate and reason on their own while practicing and applying what they know about proportions.