I was at a Girl Scout camp training this weekend for adults and we had this discussion about how much a gallon of water weighs (I think we settled on 8 pounds).
That got me thinking....would an 8 oz glass of water weigh the same as other liquids? Milk, orange juice, orange juice with plup, tomato juice?
I thought that might make a fun classroom discussion. Students could see the different liquids being poured, make observations and then a hypothesis. They could test their weighing and measuring skills to come up with the answer.