A few little things that need to be said:
CAUTION: Children at Work! Staying Safe in the Kitchen
Wash your hands! Make sure every child washes his/her hands before cooking -- and washes them again any time they sneeze, use the bathroom or cough. Don’t forget to cough or sneeze into your elbow to minimize the germs that touch your hands.
Demonstrate the proper use of utensils, especially knives. Teach children to always cut away from themselves. Save the intricate carving for yourself. Check out these scary fingers to guide children in proper knife use.
Remember that seemingly innocent utensils like plastic knives and toothpicks can become dangerous weapons in the hands of an unwary child. Always supervise closely and offer help when necessary to insure safety.
Don't sample uncooked products made with raw eggs. Yes, this means cookie dough! Raw eggs are a primary source of salmonella, a dangerous type of food poisoning. Although you may have eaten raw cookie dough your entire life, it doesn't mean it's a good idea to teach your children to do so. Instead, let them be your "official tasters" once the project is completed.