The objective of this research was to enhance two case studies of pre-service science teachers in master’s degree program teaching practices according to socio-scientific issue (SSI)-based teaching through collaborative action research. The case study participants had taken a field experience course at one of the universities in Bangkok during the 2014 academic year. The researcher gathered data from classroom observations, students’ journal entries, and student artefacts. In addition, the students were asked to write journal entries about their teaching practices. Moreover, informal interviews were used for clarification. These collected data were analysed using within-case and cross-case analyses. The findings showed that both case studies developed 10^th grade students’ argumentation skills through SSI-based teaching in a natural resource unit with four stages of teaching (the issue stage, the exploration stage, the argument stage, and the decision-making stage) for promoting student argumentation skills. Based on the collaborative action research, both cases changed their teaching practices to include more minds on activities to hook students’ interest in SSIs; an increase in student group work in order to get more essential information; the use of role play to promote effective student argumentation; and adequate time to review the data to better support decision making.