The CDC has some great resources for educators, including one on Concussions in children and sports. I just found another part of their site that has more educational resources.
BAM - Body and Mind - is a collection of resources for educators and students aged 9-13 (although you can scale the materials upward). The site has information about healthy lifestyles, diseases, stress, food and nutrition, physical fitness, safety and the human body.
The activities are fun, well-designed, and educational and can be used in a health or life science / biology course.