I taught CPR and first aid for the American Red Cross for nearly 20 years and have taught children as young as 3 years of age ballet and dog bite prevention. I think that children can learn something at any age. It's just a matter of paring down the material to their level of understanding. They can and should learn what to do in an emergency - that is how to call for help. They should learn how to stay safe and they can learn how to do CPR and some basic first aid. However, due to their limited strength and lung volume they cannot provide CPR like an adult would. That said, what they can do is dependent on their size, even more than their age. Each child is different as well, so chronological age is not the sole determining factor either. What a child can learn depends on his age, size, individual intellectual ability, temperament, etc., but every child should be taught the basics, including how to call for emergency assistance and how to stay safe.