Kids' Eating: Servings Sizes
A good rule of thumb is to offer one tablespoon (serving spoon, not measuring spoon) of food per year of age up to one-half cup. Teenagers will need larger servings depending on their height and weight.
Consider letting school-age children serve themselves, unless they are overweight. Start overweight school-age children (over 5 years of age) with half-cup servings. Let a kid eat until they stop eating and start playing with their food, then remove the plate.
Remember to model good food habits by eating the foods you serve your child. Never force a kid to eat a food he or she doesn't like, as this can lead to a power struggle.
To determine the number of servings of different food groups for different age children for a whole day, take a look inside My Pyramid.