Investigation And Research On The Status Quo Of Students' Understanding Of Chemical Reactions In Different Grades

Understanding is a word frequently used in daily life and educational research.Chemistry Curriculum Standards for Ordinary Senior High Schools(2017 Edition)proposed to "enhance the understanding of chemistry" and "improve the understanding ability of chemistry".In this context,this study measures the understanding status of students of different grades on chemical reaction.It is found that the existing research mainly tests the problem-solving ability of the subjects,which causes the subjects' cognition of some important problems such as "why is the knowledge reasonable","how is the knowledge generated",and "what is the value of the knowledge",to be ignored to a certain extent.Based on it,referring to the epistemological model of WWHW,this study defines understanding as a kind of "epistemological understanding",which refers to the subjects' cognition of "What is the meaning of the knowledge","why is the knowledge reasonable","how is the knowledge generated",and "what is the value of the knowledge".And the understanding of the above four problems is called the four understanding dimensions of knowledge,namely "understanding of fact","understanding of principle","understanding of process" and "understanding of value".Then,this study divides the knowledge of chemical reaction into six aspects: the characteristics and essence of chemical reaction,the characterization of chemical reaction,the types of chemical reaction,chemical reaction and energy,the rate and mechanism of chemical reaction,the direction and limit of chemical reaction.And this study describes the connotation and structure of the above six aspects,combes the requirements of junior high school,senior high school and university on the content of chemical reaction,constructs the knowledge system of chemical reaction,and selects the core content of chemical reaction from the six aspects.Next,according to the six aspects of the core content of chemical reaction and the four dimensions of epistemological understanding,this study compiles one general test paper and four grade test papers.After two tests,the formal testing tools and grading standards are determined.Students in eight parallel classes from grade one to grade three at two high schools and chemistry normal students of the third grade at our university are tested.And this study adopts the method of statistical analysis and case analysis to analyze the current situation of epistemological understanding of high school students at the beginning of the academic year and chemistry normal students at the end of the third academic year on chemical reaction knowledge.The result shows that high school students' epistemological understanding of chemical reactions increases with the grade;high school students who choose chemistry as the subject of college entrance examination have a better understanding of the principle and process of chemical reaction than the other students;and chemistry normal students do not have a good understanding of the deeper principles and essence behind chemical reaction knowledge in middle school.On the whole,students of different grades need to improve their epistemological understanding of chemical reaction.The result suggests that chemistry teaching in middle school should pay more attention to the application condition,principle essence,generation process and practical use of knowledge,and strengthen the teaching of micro-process,evidential reasoning and cognitive angle.The result also suggests that the professional training of chemistry normal students should pay more attention to the formation of solid discipline foundation and guiding chemistry normal students to pay attention to the relationship between the chemical professional knowledge learned in university and the chemical knowledge in middle school.