“…Anderson -- Challenges in Defining and Validating an Astronomy Learning Progression / Julia D. Plummer -- Models / Christina Schwarz , Brian J. Reiser , Andrés Acher , Lisa Kenyon and David Fortus -- Exploring Challenges to Defining Learning Progressions / Lindsey Mohan and Julia Plummer -- Developing Assessments for a Learning Progression on Carbon-Transforming Processes in Socio-Ecological Systems / Hui Jin and Charles W. …”