The National Agriculture in the Classroom website is geared towards agricultural literacy in the classroom. This site includes lesson plans, programs, and student center with interactive concepts.
The Concord Consortium provides lessons and interactive items in the area of science. This is broken down into biology, chemistry, earth and space, engineering, mathematics, and physics. You can also sort by grade level.
eGFI is a science website that focusing on engineering. It provides lesson plans and activities form grades 5-12.
The U.S. Department of Health and Human Services provides information related to multiple different science and health topics. Each category on the website is broken down into outside links to help supplement the instruction in the classroom. Some of these links also include lesson plans and units.