Why are serving sizes for 100% juice set at 8 oz, 10 oz, and 12 oz for elementary, middle, and high school, respectively, under these Guidelines?

School children ages 5-18 need 1-2½ cups of fruit each day, based on their age, gender, and physical activity level. An 8 oz. serving of 100% juice is counted as one cup of fruit towards this daily fruit requirement. Many children do not consume enough fruit. Juice makes consumption convenient and enables fruit servings to be available in schools in a form that is readily consumed by children. The serving sizes defined in these Guidelines incorporate and balance these data and provide appropriate portions for children as they grow.