Earth science is becoming increasingly important in the K-12 schools of Illinois as teachers and schools at all levels are encouraged to cover more about the formation and current state of the earth. Many teachers wish they knew more about earth science in order to effectively impart the subject to their students. The Geology/Geography Department of Eastern Illinois University offers a 17-day faculty-led field course in the earth sciences designed specifically for K-12 teachers to help remedy this lack of knowledge in earth science. Inquiry education is used throughout the course. The classroom is the great outdoors with plenty of first hand observations, group discussions, hands-on manipulation of geologic objects, demonstrations, lectures, and use of maps in settings involving sedimentary, igneous, and metamorphic processes. The sites visited by the teachers include the Badlands, the Black Hills, Devil's Tower, Yellowstone National Park, and the Tetons. The course has no prerequisites (other than being a teacher) and is designed so that beginners as well as experienced high school earth science teachers will learn. The course is very well received by teachers and a second, more advanced course was developed last year to further expand knowledge of K-12 teachers in the earth sciences.