In modern physics, the photoelectric effect is an important phenomenon for understanding the nature of light, which is one of the foundations of quantum mechanics. It is significant in the history of science in that Einstein solved the problem by prop...
In modern physics, the photoelectric effect is an important phenomenon for understanding the nature of light, which is one of the foundations of quantum mechanics. It is significant in the history of science in that Einstein solved the problem by proposing the photon theory due to the results of the photoelectric effect experiment, which could not be explained from the perspective of the wave theory of light, which was widely accepted until the early 20th century. Furthermore, the photoelectric effect can be seen as playing a key role in allowing a deep understanding of the concept of light by accepting both perspectives and reaching a new principle, the duality of light. Meanwhile, difficulties have been reported in teaching the photoelectric effect in the field based on textbooks. As a specific example, there was a study that revealed insufficiencies in the structure of photoelectric effect content in high school physics textbooks because the physics content system presented in the curriculum was not specific. As a way to solve these teaching and learning difficulties, the 2022 revised science curriculum emphasized the need to build a content system for physics subjects that contains the storyline and the essence and framework of physics. In addition, it was emphasized that students should reach the core ideas of each area by cultivating the three-dimensional content elements contained therein in a balanced manner. This can be said that the 2022 revised curriculum provides opportunities for balanced teaching and learning, thereby achieving holistic growth through in-depth understanding of the subject. And many researchers expect that this direction of the 2022 revised curriculum can be well achieved through an understanding-centered curriculum (authentic understanding). Accordingly, in order to properly construct the content system of physics subjects, it is necessary to understand what the storyline (flow) and framework (structure) that make up the content system are. However, it is difficult to specifically identify the storyline and outline that constitute the content system of the physics curriculum through the revised 2022 science education curriculum. Therefore, in this study, in order to understand the storyline (flow) and framework (structure) that make up the content system of physics subjects, the practices in science, which contains the flow and structure of physics, was introduced. Accordingly, in this study, the classic science book *The Evolution of Physics* (1938) (hereinafter, EoP), which is considered to contain the practices in science well, and the American high school physics textbook *Harvard Project Physics* (1970) (hereinafter, HPP) were selected as research subjects and the content system of the photoelectric effect was analyzed. Next, we went through a process of in-depth analysis of the characteristics of the understanding that readers of EoP and HPP would form through experiencing the practices in science. For analysis, we referred to authentic understanding in science education (Lee et al., 2024), which proposed the authentic understanding (aspect of understanding) suggested by Wiggins & McTighe (2005) in a form that can be used in science subjects. In addition, we analyzed the 2015 revised physics textbook and compared it with the results above. The results of the analysis are as follows. The major features that emerge from the analysis of the flow of the photoelectric effect content system of EoP contained in the practices of science is that it shows a major flow centered on the change in perspective on light. In an effort to properly understand the photoelectric effect phenomenon, the limitations of the existing wave theory of light have been recognized, and the flow of EoP, which moves toward a new perspective, can be seen as providing an opportunity to experience practices in science that emphasizes the historical development process and context of exploration in physics. The main features that emerge from the analysis of the structure of the photoelectric effect content system of EoP contained in the practices of science is that it shows a structure in which the content elements are logically connected centered on two contrasting perspectives on light. In addition, after introducing a new perspective, it attempted to explain the double-slit experiment based on this and further suggested the duality of light, showing a more systematic structure than HPP. The keywords of the EoP’s photoelectric effect content system were analyzed into five (photoelectric effect, light wave theory, photon theory, double slit experiment, and duality of light). The following are characteristics of the aspects of understanding that can be formed as EoP readers experience the practices in science. We can see that phenomena and experiments are explained through the perspective of light at every step of the text, and furthermore, sympathy, self-knowledge, etc. were described in a way that could be formed. The major features that emerge from the analysis of the flow of the photoelectric effect content system of HPP contained in the practices of science is that it shows the flow centered on the results of the photoelectric effect experiment. Unlike EoP, the photoelectric effect experiment results are presented all at once, and the conclusion is emphasized without sufficiently explaining why the photoelectric effect experiment results cannot be explained by wave theory. In addition, the narrative features an emphasis on the conclusion that the photon theory emerged without providing a sufficient explanation of the background to its emergence. Accordingly, it can be seen that the overall flow of HPP’s photoelectric effect content system emphasizes the flow of presenting the conclusion first. The major characteristic that emerges from the analysis of structure of the photoelectric effect content system of HPP contained in the practices of science is that it shows a structure in which content elements are connected centered on two contrasting perspectives on light. And three key words were selected for the HPP (photoelectric effect, wave theory of light, photon quantum theory). The following are characteristics of the aspects of understanding that can be formed as HPP readers experience the practices in science. In the first half of the detailed section, phenomena and experiments are explained or situations are explained through the perspective of light; In the second half of the detailed section, the text is written to empathize with the situation and form self-knowledge based on the perspective on light. As a result of analyzing the flow of content systems in the photoelectric effect area of three types of Physics I textbooks, the common feature is that the flow is rather than being visible, it shows a lack of connection between key content elements. Specifically, the wave theory of light itself was inadequately covered, and the reason why the wave theory of light cannot explain the results of the photoelectric effect experiment was not specifically explained. In addition, the logical connection between the core content elements mentioned above was analyzed to be somewhat insufficient, such as the introduction of the duality of light in a situation where the connection between the core content elements. The characteristic that appears as a result of analyzing the DC structure diagram of three textbooks is that the structure is formed in which the contrast of perspectives on light is not clear. Among the two perspectives on light, the ‘wave theory of light perspective’ is not clearly expressed as a perspective, and the logical connection between content elements is insufficient. In addition, four keywords (photoelectric effect, wave theory of light, photon quantum theory, and duality of light) were selected for the textbook. If we look at the characteristics that emerge as a result of analyzing the aspects of understanding that can be formed by students learning textbooks, we can see that the description was written to briefly explain related content overall. The results of the analysis comparing the flow of the photoelectric effect content system of EoP, HPP, and textbooks are as follows. First, the flow of EoP’s photoelectric effect content system showed a major trend centered on the change in perspective on light. Meanwhile, HPP showed a trend centered on the results of photoelectric effect experiments. In contrast, the three types of textbooks were found to have insufficient connections between core content elements rather than showing a flow. In addition, the textbook has a positive feature of including the ‘photoelectric effect application’ aspect by introducing the charge-coupled device (CCD) as an example of the photoelectric effect that is not shown in EoP and HPP. The results of the analysis comparing the structure of the photoelectric effect content system of EoP, HPP, and textbooks are as follows. First, the structure of EoP’s photoelectric effect content system centers on two contrasting perspectives on light, and after introducing a new perspective, it attempts to explain the double-slit experiment based on this and further suggests the duality of light. It can be seen that it has a more systematic structure than HPP. The structure of HPP’s photoelectric effect content system shows a structure in which content elements are connected around two contrasting perspectives on light. Meanwhile, among the two perspectives on light, the three types of textbooks did not clearly reveal the light wave theory perspective as a satisfactory perspective, forming a structure with insufficient logical connectivity between content elements. When comparing the keywords of EoP, HPP, and textbooks, the overlapping keywords are ‘photoelectric effect’, ‘wave theory of light’, and ‘photon quantum theory’, and they can be seen as essential content elements in forming the content system of the photoelectric effect. And in the case of ‘duality of light’, it was included as a keyword only in EoP and textbooks, and in HPP was not included. The keyword included only in EoP is ‘double slit experiment’, because the EoP text included an attempt to explain the double slit experiment based on a new perspective. The results of the analysis comparing the aspects of understanding expected to be formed by readers of EoP, HPP, and textbooks are as follows. First, EoP explains phenomena and experiments through the perspective of light, and furthermore, the text is written to build empathy and self-knowledge. On the other hand, HPP describes the phenomena and experiments or explains the situation through the perspective on light in the first half of the detailed section, and in the second half of the detailed section, the text is written to empathize with the situation and form self-knowledge based on the perspective on light. Meanwhile, the textbook’s overall narrative characteristics were revealed to briefly explain related content. Through the analysis results of this study, it can be seen that EoP and HPP have tried to contain the practices in science in common and contain descriptions that can help readers reach a authentic understanding of the photoelectric effect. On the other hand, it is difficult to say that the textbook contains practices in science well compared to EoP and HPP, so it seems difficult for students to form a true understanding of the photoelectric effect content through it. However, it is necessary to consider that textbooks have institutional limitations, and the latest scientific and technological contents of current textbooks need to be considered in the development of the textbook content system. Therefore, summarizing the research results, it seems that EoP, which contains the practices in science well, is described so that students can form a better understanding(authentic understanding) than other textbooks. This study appears to be able to help provide direction in appropriately constructing the photoelectric effect content system through the practices in science. keywords : Photoelectric Effect, Content system, Practices in Science, Authentic understanding, The Evolution of Physics, Harvard Project Physics, Textbooks, 2022 revised science curriculum student number : 2020-20264