In recent years, constructivism is regarded as one of the great ideas in education. Its implications for the way teachers teach and learn how to teach are enormous. If our efforts to reform education for all are to be successful, then we must focus on the student. By far, the focus on student-centered learning may be constructivism's most important contribution. Therefore, within this article, constructivist learning theory is discussed as a paradigm of teaching and learning at high schools in Vietnam. Constructivism is a learning theory found in psychology that explains how people can acquire knowledge and learn, thereby directing application to education. Conceptual understanding of the theory as well as the basic characteristics of constructivist learning environments was discussed in more depth. Five basic principles of constructivist teaching, twelve characteristics of a constructivist teacher and six constructivist benefits have been outlined in this article. Furthermore, the significant differences between the traditional classroom and the constructivist classroom were highlighted and several implications of constructivism for teaching and learning were reviewed. Therefore, the study draw a conclusion that high-school teachers need to think about their practices in order to apply these ideas to their work, and constructivist teachers encourage students to continually assess how the activity helps them understand.