Here is a fourth grade unit on Nutrition with Web sites to visit as well as a teacher's page complete with rationale, objectives, activities, and evaluation procedures. Students will learn about the food pyramid, nutrients, vitamins, and more. Some knowledge on how to navigate on a browser. The directions and sites and sctivities are all on this site. You can complete the unit with no other materials, but the more provided to the students, the better.
Fourth graders are old enough to share responsibility in their nutritional decisions.
It is important,therefore, that they can identify healthy foods, recognize a serving size, and develop good eating habits at an early age. They do research on a dozen or so web sites and keep notes on what they learn. There are several activities they must complete during the course of the study. There is a final project in which they must plan healthy meals. There is an evaluation rubric on the teacher's page.