This study investigates the effect of a training course, based on constructivism, on the student teachers' perceptions of teaching, learning and the roles of teachers and students in the teaching-learning process. A sample of 188 student teachers (92 of them in the experimental group and 96 in the control group) from the Hashemite University were subjected to a pre-test that was developed and validated for the purpose of the study, and the experimental group was then trained using a four-step training course based on constructivist ideas. Results showed that the two groups' perceptions were not consistent with constructivist ideas before the training took place, but after training, there were significant differences between the two groups' perceptions about the four areas. Also, there were significant differences between the constructivist perceptions of males and females, with females' perceptions being more consistent with constructivist ideas than males. The study concluded with recommendations concerning the introduction of constructivist ideas in educational courses that are designed to prepare student teachers for science teaching, and further research to examine the effect of this course on the student teachers' practices in the classrooms.