CK-12 Foundation
Ck 12: Fifth Grade Science: Earth Science: Earth's Motion in Space
[Free Registration/Login may be required to access all resource tools.] Discusses the motion of the Earth with its day and night cycle, the seasons, the Earth's orbit around the Sun, and its year-long cycle.
University of Texas at Austin
The University of Texas Mc Donald Observatory: Shadow Play
Everyone and everything has a shadow. Shadows illustrate how three-dimensional objects can be viewed in two dimensions.