Laboratory Earth, a series of three NASA-Sponsored, on-line graduate courses for K-8 teachers, was designed to meet a variety of learning styles and appeal to teachers' motivation to learn the content and improve their teaching. This is especially important to teachers as they seek to demonstrate "highly qualified" status to meet No Child Left Behind standards. These graduate-level courses consist of four modules of two to four lessons each. Pre- and post-course surveys indicated significant increases in teachers? (n = 51) content knowledge, science teaching efficacy beliefs (STEBIA), sense of community within the course (LEO) and science teaching enjoyment (STES). Qualitative data indicated teachers valued the cohort system, content aligned to teaching needs, and the instructor's response to requested feedback. Results indicated that online courses can provide valuable professional development opportunities for K-12 science teachers to deepen their knowledge, sharpen their skills, and maintain their knowledge of science developments. Because teachers play an important role in the development of their student?s attitudes towards science, it is extremely important that science and education communities collaborate to create courses that use contemporary pedagogy to address the content-knowledge needs of teachers required by National Science Standards criteria.