Serving sizes. Basically it looks like a whole fruit (apple. Orange) is considered a serving, but I don't think they shop at Costco. 1/2 cup is good for fruit or veggies or 1 cup for lettuces.

Toddlers needs 1/2c./DAY of veggies, kids 4-8 yrs need 1-1.5c

From:http://nutrition.about.com/od/fruitsandvegetables/f/servingfruit.htm