You’ve heard the statistics: According to the Centers for Disease Control and Prevention, 20 percent of kids ages 6 to 11 are now considered obese, up from only 7 percent in 1980. You probably also know two key weapons against kids’ increasing girth: more exercise and a lot less junk food and soda. But sometimes it’s hard to tell whether something that sounds good (“All-natural granola bar for healthy energy!”) actually is healthy for growing children.

Of course, the best foods are those in or close to their natural state, with zero to minimal packaging: whole fruits, crispy vegetable sticks, nut butters without additives, fresh water. But when convenience dictates a packaged food, the logical next step is to educate kids how to evaluate it. And that means understanding food-label basics.

It’s not just kids who can be intimidated by labels. In a 2011 survey of 1,009 U.S. parents, 42 percent said that understanding nutrition labels is more difficult than interpreting assembly instructions for IKEA furniture. As long as your child can read, he doesn’t have to be a scientist to make better food choices. Here’s how to gently teach what a food label is really saying.

1. Scrutinize ingredients.

“If you see artificial colors and flavors, artificial sweeteners, high-fructose corn syrup, or partially hydrogenated anything, those are good signs the food is of lower nutritional quality,” says Tara DelloIacono Thies, RD. Make it a game to see if kids can sound out items in the ingredient list. It’s a classic teaching moment: Unpronounceable ingredients often mean it’s a fake, lab-created “food.” Then ask them to read the label on an apple. Surprise! No food label means it’s a whole, real food—the best, most nutritious kind.

2. Visualize serving sizes.

Nutrition numbers may look OK until you notice that a package typically eaten in one sitting is calculated for three servings.Get out two or three packaged foods, preferably items that your child eats regularly—cereal, oatmeal, applesauce—plus a measuring cup. Show her the serving-size number on the package label, and let her measure out a single serving. This visually reinforces serving sizes, the first number anyone should look at on a food label. Try it with soda or juice bottles, too, which often say “2 servings.”

Also, most nutrition labels’ serving sizes are based on an adult’s 2,000-calorie diet. For kids ages 4 to 8, portion sizes should be about two-thirds of an adult portion; for preteens, portions should be 80 percent to 90 percent of the adult amount, says DelloIacono Thies.

3. Evaluate numbers.

Evaluate numbers, particularly those for calories, fat, sugar, fiber, and sodium; see “Nutrient Guidelines for Kids,” TK. (Cholesterol alone is less of a risk factor for kids than saturated fat and sugar, DelloIacono Thies says, unless your child is on a special diet.) Look for high percent Daily Values (DV%) for nutrients such as calcium, iron, zinc, and vitamin D, which can be hard to get enough of via diet alone. Make simple guidelines that feel right for your family; for example, boxed cereals that contain at least 3 grams of fiber and less than 4 grams of sugar per serving.

4. Compare and contrast.

Armed with these basic guidelines, compare, for example, the amount of sugar and calcium in a can of soda versus a carton of milk, or the fiber and calories in a serving of cooked rolled oats versus a sweetened cereal. One-to-one evaluations will begin to give your child a sense of what numbers constitute a “high” or “low” amount.

5. Let your child do the shopping.

At the store, translate knowledge into choicesby having her compare different food labels. Let her choose which one she thinks is the healthier option. With time and practice, she’ll use her knowledge to make healthy choices long after you’ve stopped watching.

Nutrient guidelines for kids (per-serving amounts for ages 5–10):

Calories: 175 or less, Saturated fat: 1 gram or less, Trans fats: 0 grams, Added sugars: 13 grams or less, Sodium: 210 mg or less, Fiber: at least 2 grams