Lewis and Clark
Free "History of Science" Lesson Plans for 6-12 gr.
Written for teachers, these are interdisciplinary lesson plans. Some consist of only one or two activities, while others could fill a semester or more. The lessons I've read are clear, fully explained, and include extensive bibliographies. Most are written with the expectation that students will be working in a group. They could a be a valuable resource for a homeschool science club.