What do the prospective science teachers know about human eye

When words in the networks are examined it has seen that PST usually used interrelated concepts such as human eye (fovea, blind spot, myopia, hypermetropia, astigmatism), human eye defects (myopia, hypermetropia, astigmatism), treatments of the eye defects (operation, concave and convex lenses, no treatment), vision keywords (the fovea, human eye, optic nerves, light). But they used words related human eye structure as the sclera and vascular layers, vitreous body slightly. Also in the open ended questions, it was seen that the PSTs knew the location of the sclera very well but they had difficulties in determining the location of the fibrous and the vascular layers. Although the PSTs responded about the location of these layers correctly, the responses of them about the functions of the layers do not show parallelism. This situation can be explained by the fact that the PSTs do not have sufficient knowledge about the functions of the layers of human eye. Also in the interview about concepts that is determined the PSTs stated that do not know the structure of human eye exactly. They explained the cause of that as they are trying memorizing learning. When the responses of the PSTs about the cornea are examined, nearly half of the PSTs know the location of the cornea both in the WAT and open ended question. But, they do not possess the knowledge that the cornea formed when the sclera layer underwent a change. Although the some PSTs know the features and the location of the iris, it is revealed that they do not possess the knowledge that the iris formed with the changes in the vascular layer. They explain function of the iris color give to human eye. They don’t aware of iris provides growth and shrinkage of the pupil depending on the amount of light. Although the PSTs repeated medium frequencies in the WAT, the PSTs’ lack of information about the structure of the pupil draws attention in the open ended questions. Only 2 PSTs stated that the pupil is hole in the middle of the iris. The other PSTs stated as pupil is in the middle of the iris superficially. Unfortunately, PSTs stated that they surprised when they saw that the pupil is hole in the middle of the iris in the interview. These findings supported to each other. The most of the PSTs having alternative concepts about the pupil state that the pupil is on the lens, behind the iris etc. Nearly most of the PSTs could not answer this question correctly. Similarly, in the interview the PSTs stated that they confused the ranking of organs in the eye. However, the PSTs could answer the question about pupil’s getting sometimes wider or sometimes narrower correctly with the light factor entering the pupil. The PSTs’ explanation of the pupil’s getting sometimes wider or sometimes narrower can be explained with the fact that the expansion and contraction of the pupil is frequently used in daily life because associating science concepts to daily life and their use in daily life is quite effective to learn the concept (Saka et al., 2002; Ünal & Coştu, 2005). In the interview, some PSTs stated learned associating and some PSTs stated that do not understand because they do not adapt to different cases. Similarly, nearly the half of the PSTs could not know that the crystalline lens is a convex lens. They also could not explain the function and location of the crystalline lens. In the WAT, is seen that the PSTs answered the crystalline lens word in the lowest cut-off point. Also the results of the interview are supported to this case. Rule and Welch (2008), benefited from analogy to teach the theoretical underpinning of the activities, to support elementary student learning about the structure and function of the eye. B coded PST stated that they could not understand the relationship between the lens and vision. The PSTs do not know to the refractive index of the crystalline lens can be changeable. This case is interpreted that the some PSTs possessed poor background and lack of knowledge on the crystalline lens. The some PSTs stated that the crystalline lens acts as concave lens and the some PSTs believed that the sometimes the crystalline lens acts as concave lens, the sometimes acts as convex lens. This situation can be explained with the fact that the PSTs could not construct the refraction of light through lenses in their minds. In this case is explained that the PSTs do not know the focal length of the crystalline lens can be changeable. Moreover, this situation can be interpreted as the result of the PSTs did not associate the lenses subject to the daily life while learning them in the physic course. There are realistic models elucidating the changing the focal length of the crystalline lens in the literature (Mullin, 1996). Also Dilek and Sahin (2013) suggested a teaching activity provides a context for the basic principles of image formation in thin converging lenses. So, in their class activity concerned with real image formation by a converging lens in the context of accommodation in human eyes is described. In the first part of the activity, students are encouraged to experience the accommodation of their eyes in a prescribed way using simple materials. In the second part, the accommodation function of human eye is illustrated by means of a simple demonstration. Dilek and Sahin (2013) associated geometric optic with working of human eye in their study. Ahçı (2012) in his study determined that the university students could not draw the formation of the image through convex lens, and they possessed insufficient knowledge such as the individual who is farsighted should use concave lens and the individual who is short-sighted should use convex lens. Thus, the PSTs take optics course in the undergraduate 2nd grade, as well as they acquire the theoretical knowledge about the refraction of light through lenses and practice skills (URL-2, 2013). Half of the PSTs stated correctly in what area of human eye are the macular area (fovea) and the blind spot located. Similarly, in the WAT the PSTs answered the fovea and blind spot at high frequency. Most of the PSTs could not answer the question about the route the ray follows when entering human eye and again. This situation results from the fact that the PSTs do not know the structure of human eye very well. Even though the PSTs acquired some similar knowledge about human eye from the primary education to university education, they were not able to answer these questions correctly. The reason for their not being able to answer them could be that either learning was not attained or the students memorized the knowledge without constructing it in their minds (Koray & Tatar, 2003). Already the PSTs stated that do not know structure of human eye exactly and they learned memorizing. Similarly, Glynn and Duit (1995) stated that students may think one thing but verbalize another because of memorized facts (cited by Rule & Welch, 2008). “Student ideas that differ from scientific explanations may reappear after instruction if the teacher does not directly address them. These mental models are unique and individual, but often they have inconsistencies” (Rule & Welch, 2008). In this context, the teachers are vital to provide meaningful teaching. When the PSTs’ responses to the questions about human eye defects and its treatment were examined, it is revealed that they possessed a higher rate of correct information about human eye defects and its treatment such as hypermetropia, myopia, astigmatism and diplopia which are commonly known among the public. However, they do not know human eye defects such as amblyopia (lazy eye), presbyopia, glaucoma, and trachoma very well. In parallel with this, only 3 PSTs could answer the question “what is eye defect which is also expressed as daltonism?” correctly but 31 PSTs could not answer it. However, when this question is asked using the term “color blindness”, commonly used in the socio-linguistic perspective, nearly all of them could explain the causes of the color blindness correctly. The socio-linguistic perspective in education has led to a wide recognition of the role of language in learning science (Kaur, 2012). The daltonism eye defect (the color blindness) must be taught formally in the 7th grade Science and Technology course curriculum in the primary education (MNE, 2006b). So, that the PSTs’ knowing that daltonism is color blindness is important and essential for their future careers. This condition can be explained with the PSTs’ perceptions concepts and events encountering in their daily life (Cerrah Özsevgeç, 2007; Şahin, 2013; Ünal & Coştu, 2005). Similarly the PSTs answered hypermetropia, myopia, astigmatism and diplopia defects as answer word the most often. They answered the other eye defects as daltonism, trachoma the lowest often. Rule and Welch (2008), emphasis on analogy and words with multiple meanings provides opportunities for integration with reading and language arts. Because is very important addressing students’ misconceptions, the roles of analogy and vocabulary in science learning, the theoretical underpinning of the activities, and national standards that support elementary student learning about the structure and function of the eye. Also the PSTs could answer treatments of the hypermetropia, myopia, astigmatism defects correctly in the open ended questions. But they could not answer treatments of the other eye defects. Although the PSTs stated treatments of the hypermetropia and myopia defects in the open ended questions, most of the PSTs could not draw its. The PSTs drew instead hypermetropia of myopia defect and its’ treatments. Although some PSTs could draw the eye defects correctly some PSTs could not draw its’ treatments. These results are consistent with the research results of Ahçı (2012). Even though the image was drawn hypermetropia defect in the behind of the fovea, was drawn the concave lens for treatment (see Figure 5). These findings indicate the PSTs do not know the usage aims of the lens they memorize without establishing cause and effect relationships between concepts. It is possible students do not draw because they have not sufficient knowledge (Kara et al., 2008). In the interview about concepts, the PSTs stated that they could not associated interdisciplinary their physics and biology and could not adapted to different cases. Thus D coded PST stated that she embarrassed and after then interview she'll go home and memorize thoroughly. In interview about concepts, although 6 PSTs could explain the eye defects and its’ treatments correctly, only 3 PSTs could explain the cause of the eye defect partial correctly. These PSTs explained the cause of the eye defect with “disrupting of the structure of the crystalline lens”. But they did not stated change in the structure of the major axis of the eye. Although J coded PST explained the eye defects and its’ treatments correctly, they stated the cause of the eye defects with the crystalline lens acts as concave lens. This alternative concept indicates that the PST does not know factors which affect the focal length of the lens. F, G and H coded PSTs constructed associating the eye defects with the feature of the lenses in their minds. G and H coded PSTs stated that they understood the eye defects and its treatments because of associating with themselves eye defect. J coded PST sad that he do not forget because of coding of the eye defects and treatments as KUM. It is seen that to make sense concept is very important to code, associate and establish cause and effect relationships. Similarly, Rule and Welch (2008) used object boxes to teach the form, function, and vocabulary of the parts of human eye and investigated the role of analogy and vocabulary in alleviating science misconceptions. Rule and Welch (2008) determined that students learned better through analogies the form, function, and vocabulary of the parts of human eye in their study. Answers of the PSTs were examined in the two tiered question it is determined that they have problem on how is seeing. Even though PSTs aware of light must be to see any object they do not aware of the reflected light from the object must come to eye. Furthermore only one PST could draw accordance with refraction law of light in lens correctly. But he did not draw vision, he just could draw image in the convex lens. As well as elementary school 6th grade students’ explanations in studies of Çiftçi & Çökelez (2012), the PST described “vision concept” with “image concept”. Similarly, it is determined that to see and look are perceived as the same concept in some other studies (Galili & Hazzan, 2000; Heywood, 2005, Şahin, İpek & Çepni, 2008). That PSTs do not know refraction of light in the convex lens caused they do not answer to where and how the image is formed in the between focus and peak of convex lens. Similarly, Ahçı (2012) determined that university students did not draw the image of the object between the lens and the focus in his research. This case is interpreted that the PSTs’ lack of knowledge in a discipline would be affected to learn another discipline directly. But learner with a specified prior knowledge with the subject matter and these knowledge may not be easily transferable to a different setting (Kaur, 2012). Saka et al., (2002) determined that high school students do not have sufficient knowledge on forming of image in human eye. In this context, when teaching geometric optics, human eye has great potential as a relevant context to engage students’ interest (Dilek & Sahin, 2013). The results of this study support Kaur’s results of her/his studies (2012), which “students even at the level of teacher preparation courses may not always be able to clearly articulate and analyze their own thought processes and need help to be able to do so”.
Consequently the PSTs;

Do not know the structure human eye in detail. And they have lack of knowledge on human eye.
Memorize without understanding the structure of human eye (Human eye layers, the pupil, the fovea, the blind spot etc.), human eye defects and its treatments.
Have confusing between concepts such as the hypermetropia-myopia, the fovea- blind spot, the vascular-nervous-fibrous layers, location of the iris-pupil-cornea, the function of the vascular-nervous-fibrous layers, the function the pupil-iris, the function of the pupil- crystalline lens, followed way of light when light entered human eye etc.
Do not know the cause of human eye defects and do not associate the cause of human eye defects and vision with refracting in the lens is studied at the optic course.
Could explain human eye defect and its treatments verbally, but they have the problem drawing.
The PSTs to be unrelated to physics course will affect their achievement in biology course negatively.
Not only the PSTs emphasis as the solution to overcome their learning difficulties, associating between concepts and learning meaningful but also memorizing.

This study draws attention on the potential lack of knowledge and insufficient knowledge encountered while teaching human eye. The result of this study is believed to contribute to the PSTs’ probing understanding on human eye and their learning and offer discernment to the teaching process of teachers and researchers.