National Curriculum offers a two volume series of books intended for after school programs and is geared toward 3rd-5th graders.
National 4-H Online Resources features information about agriculture in the classroom and the effectiveness of after school programs for youth development.
AgriScience offers a series of resources from a partnership between the National 4-H Council and the United Soybean Board. These resources offer an introduction to AgriScience and Biotechnology including concepts such as Agricultural Literacy, Global Food Security, Sustainability, and the variety of career paths associated with the field.
Ag 101 provides a brief overview of American agriculture, with a section specifically on agriculture.