Case Studies Of "Threefold Representatiosm" In The Construction Of Core Concepts In Senior Chemistry

The core concept in chemistry is the key point to improve the chemical core literacy.Its construction and development have pivotal position in stressing the characteristics of chemistry discipline,cultivating the ability of subject,forming the subject thought and reflecting the value of subject.It also helps to penetrate the core ideas of chemistry and helps students to set up the world outlook,view of life and sense of worth of the chemical discipline system.Finally,students can establish and form the epistemology and methodology with the characteristics of chemistry."Threefold representation" as a special way of thinking or teaching method in chemistry is widely used in the system of chemistry.The research on the teaching of chemical core concepts based on the threefold representation of "macro-micro-symbol" is not very clear.This paper deeply analyzes and compares the existing research on the construction of "threefold representation" and the core concepts in senior chemistry,and explores the relationship between them.Our research makes a further exploration of the connotation of "threefold representation" and regards it as a kind of psychological mechanism,even a mechanism of action.It includes students' internal processing of chemical concepts and the external presentation of chemical concepts based on the "threefold representation" by teachers.This paper distinguishes the difference between the core concepts and the core knowledge in senior chemistry,and pointed out that the core concepts of chemistry is superior(high level abstraction),while the core knowledge of chemistry is lower(lower level concrete),and the two are different in learning field.We put forward a new classification method based on the "threefold representation".In accordance with the main form of representation in the construction of chemical concepts,the chemical concepts can be divided into three categories: the concepts of macroscopic representation,the concepts of microscopic representation and the concepts of symbolic representation.Based on the questionnaire,we can find out whether the chemistry teachers in senior high school use the "threefold representation" in the teaching process of chemical core concepts,and analyze their attitude,thinking and practice.It also explores the students' learning process of constructing the core concepts of chemistry,indicates their learning level of "threefold representation",and draws the following conclusions: application of core concepts in senior chemical teaching based on the "threefold representation" is very deficient.Teachers and students' awareness and abilities have yet to be highlighted and strengthened.The research is based on the theory of learning process and the theory of representation system,and meticulously discusses how to apply the "threefold representation" to construct the core concepts in chemical classroom teaching.It presents teaching themes: theory of redox,theory of chemical equilibrium,theory of changing of energy in chemical reaction and proposes the design which is based on the teaching pattern of ideas construction: interpreting curriculum standards,analyzing core concepts,making clear of construction process,applying the "threefold representation",completing periodical construction,realizing spiral situation of rising.It combines specific cases:redox reaction,primary battery,limitation of chemical reaction,hydrolysis of salts,chemical energy and thermal energy,chemical reaction and changing of energy,and puts forward some teaching suggestions which can help to reflect its theoretical and practical value: transcending concepts and establishing ideas in senior chemistry,object teaching and static-dynamic combination,highlighting experiment in chemistry and breaking through difficulties,crossing disciplines and meeting the needs of social development.The purpose of the research is to use "threefold representation" to strengthen the construction and experience of core concepts in senior chemistry and construct the core ideas of chemistry.Improving the chemical literacy of students is the ultimate aim.