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Experiments are a characteristic and visual aids in teaching chemistry and they are used for a variety of purposes. Experiments can be used to develop students' capacity to use knowledge and skills through situations and foregrounds. The article presents some the following contents: Manifestations of the representation competency; Proposal of using experiments in teaching according to the flipped classroom model to develop students' representation competency; Illustrative examples in two topics of stoichiometry, nitrogen - sulfur in Chemistry Curriculum 2018 and the process of pedagogical experimentation at Nguyen Trai High School (Binh Duong) and Vinh Loc High School (Ho Chi Minh City). From the processing results, the number of definition ranges is calculated and the effectiveness of the proposed measure.

Vietnam's new general education curriculum was just released in 2018, focusing on developing students' qualities and capabilities. Chemistry is an experimental science, thus developing and assessing students' experimental competence in teaching chemistry is a very important task. Based on the experimental competence scale, the article introduced and illustrated the assessment tools for this competence including student worksheets, observation sheets, and special tests. To pilot evaluation tools, we use specifically pre-test, post-test, and worksheets affecting 63 students in grade 12 of 2 high schools in Ben Tre Province, Vietnam to collect evidence to assess students' experimental competence. Thereby assessing the feasibility and effectiveness of constructed tools.

Project-based learning related to local production is a teaching method that students learn and apply knowledge to solve a complex and practical problem. Students often work in groups, which is very suitable to develop students’ collaborative competency. This article presents two learning projects related to local production in Khoai Chau District, Hung Yen province, in teaching Organic Chemistry in grade 12. In which, the application of information technology is presented in the steps of organizing project-based learning. The proposed projects and lesson plans were pedagogically experimented with 87 students from 2 campuses of Khoai Chau High School in Hung Yen province; the learning results and the development of students' collaborative competency were evaluated. The analysis of the results confirmed the feasibility and effectiveness of the proposed contents.

The research aims to determine the effectiveness of micro teaching in developing STEM teaching organizing skills for pre-service Chemistry teachers (teaching organizing skills for pre-service Chemistry teachers - TOSfPCT). This approach was evaluated through the constructivism and experiential learning theories. This research was conducted within a course for six weeks period during the 2nd semester of the 2020-21 academic year at a Chemistry faculty, Hue University of Education. The article presents the micro-teaching process combined with the application of information technology in developing STEM TOSfPCT, pre-\post-test quasi-experimental design with control group was applied. The experiment involved applying micro teaching to the experimental group (EG) while the courses were carried out using traditional lectures in the control group (CG). Mann Whitney U Test and Wilcoxon Sign Test were used in the analysis of the quantitative data. The results obtained from Mann Whitney U Test and Wilcoxon Sign Test suggest that there is no significant difference between the pre-test scores of the experimental and the control groups. Descriptive data also demonstrated that the use of the micro teaching in the curriculum had significantly increased the skill levels of the experimental group pre-service Chemistry teachers.