Day and Night
In Texas, teachers are expected to teach day and night, both as an example of an observable pattern of change, and as a part of understanding the Sun-Earth system.
K.5 B The student is expected to observe and identify patterns including seasons, growth, and day and night and predict what happens next
4.6 A The student is expected to identify patterns of change such as in weather, metamorphosis, and objects in the sky
5.6 A The student is expected to identify events and describe changes that occur on a regular basis such as in daily, weekly, lunar, and seasonal cycles
7.13 A The student is expected to identify and illustrate how the tilt of the Earth on its axis as it rotates and revolves around the Sun causes changes in seasons and the length of a day
While the presumption is that most adults understand the cause of day and night, research has shown that many do not.
In order to understand the cause of day and night, students need to first understand that we live on a round planet, and that it turns or rotates.