Today I came across a neat little article in the newspaper about other items that can be used to "eyeball" a serving size. This may be a great guide for a youngster trying to stay healthy (not skinny).
Smartphone= 3 ounces of chicken, meat or fish.
Small thumb drive= 1 tablespoon of salad dressing, sour cream, mayo.
First generation iPod shuffle= 1 ounce of cheese.
Computer mouse= 1 baked potato.
Pedometer= 1/4 cup of raisins or other dried fruit.
One side of headphones= 1 cup of cereal, soup, vegetables, or cut-up fruit.
iPod Nano= 1 ounce of chocolate.
CD= 1 slice of bread.
AC power adapter= 1/2 cup ice cream or frozen yogurt.
Two earbuds= 1 teaspoon olive oil or peanut butter.