@Anna32 - I don't think anyone in their right mind would seriously consider showing a med school anatomy diagram to a grade school student and expect them to comprehend it. However, I do see you point and it is a good one with regard to the general population.
For anyone who was wanting to learn the basics, then a diagram of the human body like one you would see in a doctor's office is probably sufficient. But for someone wishing to gain a deeper knowledge of the body, something a bit more complex is in order. Perhaps not med school material, but certainly something a bit beyond a human body diagram for kids.