Research On Chemistry Teaching In Junior Middle School Based On Concept Construction

The concept of chemical elements, which is the core concept of middle school chemistry, is one of the important concepts in chemistry. This theory looks into the nature of the substances and their chemical changes from the elemental perspective and has a transferable consistent and lasting value. It enables learners to acquire the most valuable chemical knowledge as well as provides them with a better understanding of thinking frame so as to indicate the direction for learners’ reflection on chemical concepts.Based on the reviews on the concepts of chemical elements from home and abroad and in combination with the practical chemistry teaching in junior high school, the essay concludes the basic connotation of “the concept of chemical elements” at junior high level: the content, which can be divided into three aspects: 1. The understanding of elements, whose main points are:(1) the element is the general term of atoms which have the same number of nuclear charges(the same number of protons)(2) the atoms’ outermost electrons and valence of elements are related 2. Viewing the substance from the elemental perspective, whose main points are:(1) the substance is made up of elements(2) the substance can be classified according to the elements(3) the nature of substance is associated with the composed element, the diversity of substances result from different elements(4) the chemical formula shows the composition of substance 3. Viewing the chemical reaction from the elemental perspective, whose main points are(1) elements and atoms can reproduce new substances, but the species of elements are changeless(2) different substances produced by the same species of elements can mutually transform(3) the composition of substances from elements can be measured with experiments with the help of the law that the total species of elements always remain the same no matter before and after the chemical reaction.Through a questionnaire of junior high school students’ present understanding of the concept of elements, the author reveals that the following problems are existed in the process of students’ construction of the concept of elements: first, the students’ knowledge learning simply remains the level of memorizing without little further promotion. Second, the fundamental(elemental) understanding of aspects of substance is not available. Third, the relative understanding of chemical reactions is far from the perfect. Last, the understanding of substance fails to link to the composition of elements.Based on the summarized construction of the concept of elements and a teaching design model, the author defines the element-oriented teaching design as a process aiming to solve the essential problems, and puts forwards the concept construction-oriented strategies of chemistry teaching design as follows:(1) a variety of strategies should be applied to motivate students’ meta cognition(2) the curriculum resources should be used to organize learning activities and promote teachers’ interaction(3) students’ cognitive development should be noticed in time(4) the teaching reflection and teaching design should be emphasized. The author uses the construction of the concept of elements to design a few selected examples from Shanghai junior high chemistry textbook, with the ultimate goal of helping students construct the concept of elements. The essay’s teaching practice ends with the relevant tests on the two classes, the experimental class1, grade 9 and the comparative class 2, grade 9, with the hope to fairly evaluate the achievements of those students’ learning goals and the construction of the concept of elements.