Conference papers:

Plummer, J. D.& Krajcik, J.S. (2008). A Learning Progression for Celestial Motion.. Paper presented at the National Association for Research in Science Teaching. March 30-April 2, Baltimore, MD. Download PDF.

Plummer, J. D., Rice, R., & Zahm, V. (2008). Inquiry and Astronomy: Investigations in Celestial Motion. Paper presented at the National Association for Research in Science Teaching. March 30-April 2, Baltimore, MD. Download PDF.