Reading. If your child is learning to read, go over the recipe together before you start cooking. If he's old enough to read on his own, have him read the recipe aloud to you while you gather the ingredients and supplies.
Math. Cooking is a great way to teach and reinforce math skills in a fun, meaningful way. If your child's a toddler, she can learn number recognition and counting. Older kids can learn fractions, measuring (liquid and dry), multiplication (doubling and tripling recipes), and division (halving recipes). Your child will probably be eager to use her knowledge over and over again in the kitchen, too—it sure beats number worksheets. When math problems come up for school, be sure to point out the correlations with what you've been doing in the kitchen.
Vocabulary. You'll cover cooking terms, of course, like "preheat," "dice," "al dente," and "whip." But many general words will come up, too, such as "golden," "puffy," "blend," and "Fahrenheit." Teach your child the names of ingredients (from artichokes to zucchini) and equipment (ladles, spatulas, and whisks).
Following directions. Recipes provide the perfect practice for following step-by-step procedures. By following (or not following) them, your child can learn about consequences, too. If you find that a recipe would be better approached differently than the way it's written, make corrections in the cookbook. Also note changes you make in seasonings, amounts, etc. This will encourage your child to be on the lookout for ways to improve and personalize his work.
Frugality. By using up leftovers, budgeting food purchases, and being inventive with menus (to use in-season produce, for example), your child can learn not to waste as a matter of habit.
Recycling. Set up a good recycling system in your home, if you don't already have one, and learning to recycle those packages and cans and food scraps will be automatic.
Responsibility. Cooking is fun, but a responsibility, too. Your family is waiting for a meal, after all! Your child will also learn that it's her responsibility to clean up after herself if you make sure that she does it in the kitchen as she cooks. At the same time, she'll learn the satisfaction of contributing to the family. (You can extend this to the community by having her prepare a dish for a community potluck or an extended family get-together, too.)
Other cultures. Spice blends like Indian Curry, Herbs de Provence and Mexican Seasoning are easy ways to introduce ethnic flair—and enlightening conversation—to dinner. Look for easy-to-prepare recipes from other cultures, like Malaysian Chicken Satés for grilling night (you can marinade the chicken in the refrigerator during the day), and Italian Cheese Pie for dessert.
Related life skills. Cooking is a great foundation for teaching other life skills, too, such as meal planning and nutrition ("This is good for our eyesight," and "This will help you build muscles!"), grocery shopping, table setting, and gardening. Visit the farmer's market and the food co-op together. Let your child help you place your order online for cooking items.
Springboard to bigger subjects, too, like food miles, organics, ethical sourcing, local foods, and sustainability. You might explain that you purchase your produce from a local farmer who sells at the co-op, for example, and that you order your coffee, tea, spices and other cooking ingredients from Frontier, a company that helps the farmers who grow their products and makes business decisions with the environment and communities in mind. (The story of Frontier and Akshaya Patra, which provides meals to schoolchildren in India, is one kids can especially relate to.)