A Study On Secondary School Students' Preconception And Conceptual Change Of Image Formation

Physics concept is the foundation of physics learning and can help students establish physics knowledge system. Whether understanding the concepts of physics correctly affects students'handling physics rules directly, but the secondary school students have their own understanding about natural phenomenon according to their experience before learning the concepts of physics formally.First, a paper-pencil test consisting of open-ended questions is developed to identify the students preconceptions about plane mirror image. Then an instructional design is developed which based on students' responses and the Conceptual Change Theory. The subjects include two class of Grade 8 selected from a school of Guilin city. When finishing the teaching of the plane mirror image, a test is developed to examine the effect of the instruction method (inquiry-based instruction & the traditional instruction-which defined teachers as the instructor and students as the acceptor).The pre-test of the investigation finds that many significant preconceptions revealed by the study are:1,21.7% of the students generally believed that the image is at the surface of the plane mirror, but not located behind the mirror whose distance from the image is equal to the distance between the mirror and the object. Students generally believed that the image can be shown on a screen.2,74.7% of the students think that the inverted image is on the surface of the lake, and 6% of the students think that inverted image is on the bottom of the lake because that it can be regarded as a screen, which can catch the image.3,69.9% of the students think the size of image is independent of the position of object. If the object is close to the mirror, the image will became larger, and while it is far away from the mirror, the image will became smaller.The purpose of this study is using inquiry-based instruction and the traditional instruction on plane mirror image in two classes. After the instruction, "Post-test for Image in a Plane Mirror" is used to evaluate students' achievement. The results of this study conclude that:1,The post-test of these two classes students is significantly superior to pre-test. The test of the result shows that approaches of these two classes' students are significantly effective in conception of image, weather using inquiry-based instruction or traditional instruction.2,Analyzing the result of these two classes students, we discover that experimental class and control class have no significant differences in total, but analyzing each item of the exam, we can find that in some concepts, the percentage of the correct answers in experimental class is higher than control class, though the aggregate score of these two classes have no significant differences.In the control class, the percentage of the correct answer is 11% higher than experimental class on size of image. It is shown that doing experiment in the class which is related to the knowledge can promote students' understanding about size of image.In the experimental class, the percentage of the correct answer is 21% higher than the control class on position of image when answering the question from the real situation. This result indicates that inquiry-based instruction can make students to deal with the question from real situation.In the experimental class, the percentage of the correct answer is 21% higher than pre-test, but the percentage of the correct answer at the fourth item in the control class. We can know that students can understand the knowledge by the inquiry-based instruction and students know more knowledge but can less solve practical problems by the traditional instruction.After finishing the instruction, the control class' achievement is more significant improved than the experimental class on the position of the image. The result indicates that the traditional instruction can promote the understanding of the plane mirror concept better than the inquiry-based instruction in short time. However, the results of the post-test show that control class' achievement are the same as experimental classes after a month.In this study, it is discovered that it is difficult for students to solve some questions from real situation, though they have good understanding of the knowledge about plane mirror.Half of the year later, the two classes' students have done a text which uses the post-text paper. The result between the experimental class and the control class has no significant differences, but is batter than the former one. To contrast the result between this text and the post-text, we can find that the control class is batter than the experimental class in the second question, and has significant differences, But less the experimental class about the location of image in the third question which from the real situation. The result shows that the experimental class is superior to the control class in the question which from the real situation using inquiry resources in teaching.