EL RECEPTOR CD28

There are many possible causes of difficulties encountered when learning about moon phases. These include lack of personal experience of phenomena associated with phases of the Moon, and inability to imagine looking at spatial objects from different perspectives.

Lack of personal experience of concepts associated with moon phases

Several responses demonstrate that some people lack personal experience of concepts associated with moon phases. For example, some people are not able to correctly reason about moonrise and moonset (the Moon generally rises in the east and sets in the west. Each day the Moon rises about

50-60 minutes later as compared to the previous day). Ogan-Bekiroglu (2007) asked 36 pre-service

teachers to answer questions about moonrise and moonset. Only 14% of the participants gave scientifically acceptable answers. Six percent incorrectly said that the Moon rises in the west and sets in the east, 36% said that the Moon does not rise and set (suggesting that they were not aware that the Moon appears to rise and set as seen from Earth due to the Earth‘s spin), while the rest gave other scientifically unacceptable explanations. These responses indicate that the majority of the participants had poor conceptual understanding of the rising and setting of the Moon. Some of the participants giving these conceptions claimed to have seen the Moon in the sky. Ogan-Bekiroglu suspected that they had not paid full attention to movement of the Moon in the sky.

More recently, Plummer and her associates conducted a series of studies investigating primary school students‘ and pre-service teachers‘ ideas about motion of celestial objects including the Sun, the Moon and the stars (Plummer 2009a, 2009b; Plummer & Krajcik, 2010; Plummer, Wasko & Slagle 2011, Plummer, Zahm & Rice, 2010). The majority of their participants believed that the Moon rises and sets in opposite sides of the horizon. However, some gave responses suggesting that (i) the Moon does not move, but is fixed in one location in the sky, (ii) the Moon does not rise and set, but circles the sky, and (iii) the Moon rises and sets at the same location in the horizon. Incorrect ideas about moonrise and moonset suggest that the participants did not fully understand facts associated with the Earth‘s spin.

Another point illustrating that some people lack personal experience of astronomical phenomena is apparent lack of awareness of shape of the Moon seen in the sky during different phases. Trundle and her associates have conducted several studies intended to improve students‘ and pre-service teachers‘ understanding of concepts associated with phases of the Moon. Their research usually required participants to make daily moon observations, recording shape of the Moon observed each day over a nine-week period. In three of their studies, Trundle and her associates asked 50 pre- service teachers (Bell & Trundle, 2008), 21 Grades two-to-three students (Hobson et al., 2010), and 20 Grade 8 students (Trundle et al., 2010) to draw shapes of the Moon they expected to see before making moon observations. Results show that 98% the pre-service teachers, 95% of the Grade 8 students, and all of the Grades two-to-three students drew at least one shape incorrectly. Sixteen of the pre-service teachers had completed at least one course in astronomy. Fifteen of these participants drew at least one non-scientific shape. The number of non-scientific shapes ranged between 2 and 12. These results show that some pre-service teachers had poor conceptions about phases of the Moon even after instruction.

In a separate study, Plummer (2009a) asked 60 primary school students whether the Moon in the sky changes shape as seen from the Earth. She asked the students to draw (or describe) the Moon. Fifty three students drew at least two phases of the Moon correctly. Of the remaining seven learners, two could not draw or describe the Moon at all while 5 made drawings that were all inaccurate. These results show that some students and pre-service teachers have inaccurate conceptions about the changing shapes of the Moon.

Inability to mentally perform simultaneous rotations and revolutions

Another possible cause of these problems is that some respondents struggle to mentally perform simultaneous rotations and revolutions. For example, some people struggle to understand why only one side of the Moon is visible from earth (the Moon spins on its axis at the same rate as it orbits

the Earth due to a phenomenon called tidal locking. As a result, earth viewers see only one side of the Moon). Ogan-Bekiroglu (2007) asked 36 pre-service teachers to explain whether earth viewers

see the same side of the Moon throughout the Moon‘s orbit around the Earth. Only 6% of the participants gave the correct answer, saying that earth viewers see the same side of the Moon because the Moon spins on its axis at the same rate as it orbits the Earth. Fifty six percent said that we see the same side of the Moon, but could not give a correct explanation. Thirty six percent said that we do not always see the same side of the Moon. When asked the same question, 46% of 98 secondary school students (Dove, 2002), 25% of 448 junior high school students (Trumper, 2001a), 20% of 378 senior high school students (Trumper, 2001b), and 20% of 76 university students (Trumper, 2000) gave the correct response. In addition, 10% of 251 university students in Zelik, Schau, and Matten‘s (1998) study gave the correct answer in the pre-test, while 40% gave the correct answer in the post-test. These responses show that several participants had poor understanding of the rate of the Moon‘s rotation and the rate of the Moon‘s orbit around the Earth.

Inability to imagine looking at spatial objects from different perspectives

Another possible cause of these difficulties is people‘s inability to imagine looking at astronomical phenomena from different perspectives. For example, some people struggle to imagine looking at the Moon from different locations on Earth (in each day, viewers from all parts of the Earth see the

same phase of the Moon). Several researchers asked participants to state whether the Moon appears

to be in the same phase to viewers at different locations on earth in one particular day, e.g. Full Moon in Indiana and Australia (Schoon, 1992), Full Moon in New York and California (Rider, 2002), Full Moon in Turkey and America (Ogan-Bekiroglu, 2007), Full Moon in USA and Australia (Mulholland and Ginns), and First Quarter in Johannesburg and Australia (Mulholland & Ginns, 2008). Table 2.2 illustrates results found by these researchers.

Table 2.2 Learners’ ideas about shape of the Moon seen from different locations on Earth (reported in literature)

Authors Participants Moon phase and locations on Earth

Percentage of participants giving correct responses

Schoon (1992)

1213 elementary, high school and university students in Indiana

Full Moon in Indiana and

Australia 53

Rider (2002) 32 middle school students in New York

Full Moon in New York and

California 10

Ogan-Bekiroglu (2007)

36 pre-service teachers in Turkey

Full Moon in Turkey and

America 39

Mulholland & Ginns (2008)

72 pre-service teachers in Australia

Full Moon in USA and in

Australia 51 in pre-test, 79 in post-test First Quarter in

Johannesburg and in Australia

33 in pre-test, 53 in post-test

Most of the researchers asked participants about Full Moon, while only one study asked participants about First Quarter (Mulholland & Ginns, 2008). The table shows that about half of the participants gave correct responses in Schoon and Mulholland and Ginns‘ studies (before intervention in the latter study). However, fewer participants gave correct responses in other studies e.g. 10% of 32 middle school students in Rider‘s (2002) study and 39% of 36 pre-service teachers who participated in Ogan-Bekiroglu‘s study. These responses suggest that very few participants knew that the Moon would appear to be the same for viewers at different locations on Earth. This, in turn, suggests that the majority of participants struggled to imagine looking at the Moon from different locations on Earth.

Another point illustrating this difficulty is peoples‘ inability to link phase of the Moon, time of day, and the Moon‘s location in the sky. Most researchers who investigated people‘s understanding of this link focused on the Full Moon phase, requiring participants to determine time of day when Full Moon rises (Zelik et al., 1998; Mulholland & Ginns, 2008) and time of day when Full Moon sets (Rider, 2002; Ogan-Bekiroglu, 2007). However, Mulholland and Ginns included questions about

position of crescent moon at sunset and time of day at which Last Quarter sets. Table 2.3 illustrates results obtained by these researchers.

Table 2.3 Students' ideas about moon phase, the Moon’s location in the sky and time of day (reported in literature)

Authors Participants Moon phase, Moon’s location and time of day

Percentage of participants who gave correct

responses

Zelik et al. (1998) 251 university students in New Mexico

Local time if Full Moon was

rising in the east 54 in pre-test, 75 in post-test

Rider (2002) 32 middle school students in New York

Position of Full Moon at

sunrise 6

Ogan-Bekiroglu (2007)

36 pre-service teachers in Turkey

Position of Full Moon at

sunrise 72

Mulholland & Ginns (2008)

72 pre-service teachers in Australia

Where to see Waxing

Crescent moon at sunset 8 in pre-test, 24 in post-test Time at which Last Quarter

moon sets 4 in pre-test, 6 in post-test Phase of the Moon that rises

at sunset 13 in pre-test, 25 in post-test

The table shows that 72% of pre-service teachers (Ogan-Bekiroglu, 2007) and 54% of university students (Zelik et al., 1998) gave correct answers for these questions (performance of the university students increased to 75% after an intervention). However, only 6% of middle school students (Rider, 2002) and 8%, 4% and 13% of pre-service teachers (Mulholland & Ginns, 2008) gave correct answers for these questions. Performance of the pre-service teachers who participated in Mulholland and Ginns‘ study improved only to 24%, 6% and 25% after an intervention which required the participants to make daily moon observations for at least one complete circle of phases. Poor performance after intervention suggests that the intervention was not effective in helping the teachers to understand relationships between position of the Moon in the sky, time of day and corresponding phase of the Moon.

A further point illustrating this problem is people‘s inability to imagine viewing the Earth from the Moon. Martinez-Pena and Gil-Quilez (2001) asked 78 pre-service teachers to explain a situation in which an astronaut could see the Moon in its Last Quarter phase when Earth viewers see Full Moon. To get the correct answer, participants needed to determine the configuration of components of the Earth-Moon-Sun system responsible for Full Moon seen from the Earth, and to determine a position in the sky from which the Moon would appear to be in its Last Quarter phase. Some participants drew diagrams that correctly explained the situation (Martinez-Pena and Gil-Quilez did not report frequencies). Some participants drew correct diagrams but gave wrong explanations (suggesting that the participants did not fully understand the situation). Others drew incorrect diagrams,

suggesting that they struggled to visualize the situation explained in the question. In another study, Rochford and Sass (1988) administered a multiple-choice test which had a question asking participants to determine phase of the Earth seen by an astronaut on the Moon if the Moon appeared to be crescent-shaped as seen from the Earth (similar to Question 8 in Appendix B of this study). Sixty seven percent of the participants obtained a correct answer for this question (Rochford and Sass did not report the total number of participants). Results obtained in these two studies show that some students struggle to imagine seeing the Earth from the Moon.