CTS Guide: Earth, Moon, Sun System, pp 234-235- Section IV Research Summaries

Explanation for Phases of the Moon

  • A study by Wilhelm (2014) concluded that very young children are less apt to think Moon phases are caused by a shadow because of primitive understandings about shadows they have at that age.

  • Subramaniam and Padalkar (2009) conducted a detailed study of conceptual change related to Moon phases among eight graduate students, and found that “a major source of difficulty for the participants was to understand that the Earth’s rotation or the observer’s position on the Earth has no causal role in the occurrence of the lunar phases, but only determines when and whether the Moon is visible at all” (Subramaniam and Padalkar 2009, p. 409).

  • Explanations of Moon phases as well as seasons are very challenging to students and adults. Students may not be able to understand explanations of these phenomena until they can reasonably grasp ideas about the Earth-Sun-Moon system, including relative size, motion, and distance (AAAS 2009).

  • A study by Wilhelm (2009) probed young children’s (ages 6–8) thinking about Moon phases and why the Moon’s appearance changes. These children described the Moon as sometimes looking like a banana and other times like a circle. They said that these shapes were due to the sky hiding portions of the Moon and that the Moon could change its appearance at will.

  • A research review of 27 studies about children’s and adults’ understanding of Moon phases and eclipses (Kavanagh, Agan, and Sneider 2005) found that a common misconception is that Moon phases occur when the Moon enters the Earth’s shadow. That is a correct explanation for a lunar eclipse, but not for Moon phases. Findings from studies that attempted to teach students of various ages about the cause of Moon phases indicated that instruction is likely to be effective only for students in grades 5 and above. Furthermore, a large percentage of adults, including many teachers, are unable to separate the explanations for Moon phases and eclipses, suggesting that high school and college students can also benefit from instruction on this topic (Kavanagh, Agan, and Sneider 2005).

  • In a study of preservice teachers’ ideas about Moon phases, Trumper (2001) reported that 16% of the preservice teachers he probed thought that lunar phases were caused by the Earth’s shadow, while 29% believed they were caused by the Sun’s shadow.

  • Stahly, Krockover, and Shepardson (1999) examined third graders ideas about Moon phases prior to instruction. Of the four children interviewed, all described the Moon as revolving around the Earth, but none indicated the role of the Sun with regard to Moon phases.

  • Baxter (1989) investigated students’ ideas about Moon phases and identified five predominant ideas, including the correct one (which is that a portion of the Moon reflects light depending on our position in relation to the Sun and Moon). All four of the incorrect ideas involved a shadow: (1) clouds cover part of the Moon, (2) planets cast a shadow on the Moon, (3) the shadow of the Sun falls on the Moon, and (4) the shadow of the Earth falls on the Moon.

  • In a study by Sadler (1987), 37% of the students sampled thought Moon phases were caused by the Earth’s shadow.

Moon Phases by Location

  • Schoon (1992) gave a written questionnaire to 1,213 elementary, secondary, and adult students in which they were asked if people in Australia and the United States saw the same phase of the Moon on the same night. More than half (52%) chose the misconception that people would see a different phase of the Moon. Although older students tended to do better, the differences within the age groups were greater than differences between groups. After the students answered the questions, the researcher led a discussion. Students reported that they found the problem to be very difficult, and most used one of two means to solve it: either imagining themselves in space looking back at the Earth and Moon, or recalling that Moon phases are sometimes listed on calendars, suggesting that phase is independent of location.

  • Rider (2002) interviewed 32 middle school students representing a range of ability, effort, and academic success in science who had recently learned about the Moon in school. When the students were asked: “If there is a full Moon today in New York State, will there be a full Moon today in California?” only about 10% of the students recognized that observers in both locations would see the same Moon phase on the same day.

Moon in Daytime

  • A study of 20 first-grade students in a small Midwestern school revealed that 40% believed the Moon could be seen only at night. By third grade, 80% of the 20 students surveyed knew the Moon was visible during the daytime (Plummer and Krajcik 2010).

  • Children’s early ideas about the Moon include the belief that the Moon is visible only at night or is in some way connected with the occurrence of night (Vosniadou and Brewer 1994).

Eclipses

  • Phases of the Moon are often explained using the idea of a shadow of the Earth cast on the Moon, thus confusing eclipse phenomena with Moon phases. Students’ understanding of eclipse phenomena may be related to their lack of understanding of the relative sizes and distances apart of the Sun, Earth, and Moon. Many students draw these objects so they are the same size or between half and double each other’s size. They also draw the Sun and Moon within one to four Earth diameters away from the Earth (Driver et al. 1994).

Relative Size of the Sun, Earth, and Moon

  • Mustafa (2007) interviewed students in Turkey who were approximately 14 years old, corresponding to ninth-grade students in the United States, concerning their ideas about the relative sizes of the Earth, Sun, and Moon. Of the 64 students interviewed, 28 (43%) knew that the Earth is smaller than the Sun and larger than the Moon; 10 of those who gave the correct answer (16% of the total number interviewed) could also say approximately how many times larger the Sun is than the Earth and the Moon. However, when the researcher asked the students to draw the Earth, the Sun, and the Moon, none of them attempted to show the correct scale; and when asked about the inconsistency, they were not able to explain. The author concluded that “the students may have memorized the size of the Earth, but their alternative frameworks remained unchanged” (p. 46).

  • Jones, Lynch, and Reesink (1987) interviewed 32 children from the third and sixth grades in Tasmania, asking them to pick out three-dimensional shapes and sizes to illustrate their understanding of the shapes and sizes of the Earth, the Sun, and the Moon. Only 25% of the children indicated that the Sun is larger than the Earth and that the Earth is larger than the Moon. Although there were no gender differences among the third graders, in sixth grade seven of the boys chose the correct order of sizes and only one girl chose the correct order.

  • Sadler (1987) interviewed 25 ninth-grade students about their ideas concerning the Earth, the Sun, and the Moon. About half of the students had just taken an Earth science course that included a major portion on astronomy. The students were asked to draw the Earth, the Sun, and the Moon. Nearly all of the students’ drawings showed the Earth, the Sun, and the Moon to be about the same size or within a factor of 2 of each others’ diameters—even though the Earth is 4 times the diameter of the Moon and the Sun is more than 100 times the diameter of the Earth.