This study determined the effect of constructivist method in students’ mathematics achievement. It sought to answer the influence of teaching methods in students’ achievement scores in large classes in terms of knowledge, comprehension, application, and analysis questions. A pretest- post test quasi-experimental control group design was used. The experimental group was exposed to constructivist method while the control group to traditional method. To determine the influence of the methods in the students’ achievement scores, the one way ANCOVA was used. The researcher handled the two classes. Results showed that there was a significant difference in the students’ achievement scores in terms of knowledge, comprehension; application and analysis questions. The control group performed better than the experimental group in all levels of questions. Constructivist approach is ineffective in large classes while the lecture method is an appropriate teaching approach for large classes.