3. Method
Twelve middle school mathematics teachers, six male and six female, participated to the research. Four of the teachers have experience over 10 years, and the other four have 5-9 years experience. In this research a web site has been prepared for teaching problem-solving strategies. Through this web site, a professional development study was organized during seven weeks for mathematics teacher. By considering the subject and the purpose of the research, the web site included content and pedagogical content knowledge about mathematical problem-solving strategies. The content of the web site is designed by considering problem-solving strategies which were suggested national mathematics curriculum. Web-based professional development study was organized as asynchronously aiming to provide a flexible for teachers to follow the study in a flexible manner. Also a forum section has been established in the web site. In this study, some strategies such as looking for pattern, making systematic list, making a table, drawing a graphic and diagram, working backward, writing an equation have been comparatively explained. Qualitative research methods were used for this study. The data was collected by using various instruments such as pre- and post-test, semi-structured interviews, observations and written documents.Pre- and post-test was carried out before and after, web-based professional development study for the participating teachers. The test is composed of 8 questions. The aim for using this test was to identify problemsolving strategies that teachers used during in actual classroom practices. Pre- and post-test were created by considering opinions of two mathematics education researchers together with the researcher. The content of the questions were aligned with the national mathematics curriculum. The questions were adopted from the pool of questions that were included in previous research. During the research, the researcher loaded several questions to the forum section, so that teachers explained their opinions to the questions. Semi-structured interviews were conducted with six of the participants. Questions that were used in the interview have been prepared to cover all dimensions of the research problem. The interviews, tried to uncover not only teachers' opinions about mathematical problem - solving strategies, but also their opinions about the importance of problem-solving strategies and the importance of the web-based professional development study in the strategies they use. After completing the web-based professional development study, three of the six teachers that have been interviewed were selected to observe their classroom practices. Observations have been performed one month after the completion of the web-based professional development study. Each teacher was observed during three weeks, six hours in total, in their own classes. The data have been examined by content analysis in an inductive strategy.