The day-and-night cycle forms the basis for understanding many other natural cycles in plants, animals, and Earth processes, as well as later learning about the solar system, and it is part of the National Science Education Content Standard D, Earth and Space Science, for grades K–4. Learning about light is part of Content Standard B: Physical Science Light, Heat, Electricity, and Magnetism. When studying this topic in early childhood, it is appropriate to focus children’s attention on the Sun and its movement across the sky through discussion and observation (AAAS 1993). The observations are indirect evidence of the Earth’s movement, a concept the children will become ready to understand in later years.