Our second grader need to know if something holds more than or less than a cup. It is pretty basic. After reading Room For Ripley we expanded the lesson a bit with Measurement Man. It was so cute... the kids starting quizzing each other with measurements while they were cutting them out. "Karlton... if I only have quarts, but in all it equals a gallon. How many quarts do I have?" I love these kiddos!