The Daytime Moon
Keeley, Page, Science and Children
The familiar adage "seeing is believing" implies that children will recall a particular phenomenon if they had the experience of seeing it with their own eyes. If this were true, then most children would believe that you could see the Moon in both daytime and at night. However, when children are asked, "Can you see the Moon in the daytime?" many will say "no," even though they have actually seen the Moon many times in the morning or afternoon sky. The formative assessment probe, "Objects in the Sky," (Figure 1) shows how persistent the belief is among elementary-age children that the Moon can only be seen in the nighttime (Keeley, Eberle, and Tugel 2007).
Understanding where the Moon is located at different times of the day and its changing appearance as viewed from Earth are important goals for learning. In the early elementary grades, the Benchmarks for Science Literacy state that by the end of second grade, students should know that "the Sun can be seen only in the daytime, but the Moon can be seen sometimes at night and sometimes during the day. The Sun, Moon, and stars all appear to move slowly across the sky" (AAAS 2009). The newly released A Framework for K-12 Science Education (NRC 2011) states that by the end of second grade, students should understand that "Patterns of the motion of the Sun, Moon, and stars in the sky can be observed, described, and predicted." Building on this earlier idea, by the end of fifth grade, students should understand, "The orbits of Earth around the Sun and of the Moon around Earth, together with the rotation of Earth about an axis between its North and South poles, cause observable patterns. These include day and night; daily and seasonal changes in the length and direction of shadows; phases of the Moon; and different positions of the Sun, Moon, and stars at different times of the day, month, and year."
To achieve an understanding of these important learning goals, elementary students should have the opportunity to observe the position and phases of the Moon in both the daytime and nighttime sky and discover the cyclic pattern of Moon phases by analyzing their recorded observations. This experience is one of several critical prerequisites to constructing an explanation for the phases of the Moon. Before students engage in monthly observations to discover the pattern of Moon phases, consider using a probe such as "Objects in the Sky" to find out whether students recognize that the Moon can be seen in the daytime.
With Their Own Eyes
Parts of this probe are based on research conducted on children's ideas about the Moon. Vosniadou and Brewer (1994) found that many young children believe that the Moon is only visible at night and the occurrence of the Moon in the sky is associated with nighttime. Some students will even attribute the appearance of the Moon as a causal factor for night. Research has also revealed that some students believe the Moon rises straight up in the evening, stays at the top of the sky throughout the night, and then sets straight down (Plummer 2009). When children are asked why they think the Moon is only visible at night, they often explain their thinking using this "up-down rule" and may even confuse it with the rising and setting of the Sun.
Do these ideas change with age? Consider using the "Objects in the Sky" probe or asking the question, "When do you see the Moon: daytime, nighttime, or both?" across multiple grades from first- through fifth-grade. Share your data and look for differences in students' ideas. Probe further to find out why students think the Moon is only visible during the evening. If students believe the Moon can be seen in the daytime, probe to find out what phases they think can be observed during the day. Consider other factors that may have influenced their thinking that the Moon is visible only in the nighttime. For example, children's storybooks, trade books, and instructional materials almost always show the phases of the Moon in a dark, nighttime sky. …