The purpose of this study is to investigate the effects of teaching technologies and material development course taught through Moodle based online argumentation implementation on critical thinking disposition of third year science teacher candidates. The study was carried out with a total of 43 students consisting of an experimental group of 22 and a control group of 21 students studying at the Department of Science Education at a State University Faculty of Education in the fall term of 2014-15 academic years. Sequential explanatory design was used as a mixed method strategy in this research. A quasi-experimental pre-test/post-test non-equivalent control group design was used in the quantitative part of the study. A case study research design was used in the qualitative part of the study. California Critical Thinking Disposition Inventory was used as data collection tool. In addition, an open-ended interview questions form was used to define opinions of science teacher candidates about the method applied in the course. Independent samples t-test and paired samples t-test were used in the analysis of quantitative data. Descriptive analysis was used to analyse qualitative data. At the end of the research, while a statistically significant difference in critical thinking dispositions of teacher candidates was observed in favour of post-test results of the experimental group, no statistically significant difference was observed in the control group. When the opinions of teacher candidates on the subject were investigated, it was found that the teacher candidates strongly supported the elimination of internet connection problems to improve the course.