This research was conducted in the fourth grade of a private primary school in Gaziantep in 2018-2019 academic year in order to provide pupils with critical thinking skills. This study was conducted as a qualitative case study. 23 pupils participated in the programme. In a two-month study, they were given 22 journal writing titles to improve their critical thinking skills. They wrote their journals for 5-10 minutes at the beginning of lessons. At the end of the process, the pupils and the teacher were asked to write their views about the critical journal writing programme in the form of an interview. Data were analysed by means of NVIVO 12 for Mac. According to the findings, critical thinking and writing activities positively affected the pupils’ development of critical thinking skills.