In this study we reveal that there were positive changes after the practicums of pre-service math teachers, in that, they changed contents of class and the way of explanation in order to enhance students' understanding, and provided opportunities for students to participate in the class. In addition, they made more use of textbooks in their class instead of depending on their experience acquired before the practicums. However, no difference was found before and after their practicums, neither in their review of lessons nor in their use of simple 'question and answer' strategies. In this regard, we suggest continuous researches be conducted in order to enhance pre-service mathematics teachers' teaching ability, especially those which is hard to be acquired in a short period of time. And, reflecting the results of the research, systematic development and operation of the curriculum are required in the teacher training institutes.