Why are the fundamental concepts of astronomy so difficult for our students? Many teachers of astronomy at pre-college and college levels view students as illprepared for their courses. Students do not understand fundamental concepts on which teachers hope to build. Students are not familiar with the motions in the heavens, the moon's phases, the earth's seasons, the nature of light, or the sizes and scale of astronomical systems. The graphical and visual representations that we use throughout our courses (spectra, light curves, H-R diagrams) appear foreign and strange. Equations and simple order-of-magnitude estimations are within the experience of our students, but are rarely useful to them or reproducible by them.
Sadler, P. M. (1996). Astronomy’s Conceptual Hierarchy. In J. A. Percy, Astronomy education: current developments, future coordination Astronomical Society of the Pacific Conference Series (Vol. 89, pp.46-60). San Francisco, CA: ASP