The aim of this study is to examine to what extent and how fourth-grade students use their critical thinking skills in real-life situations. The method of the research is instrumental case study, which is one of the qualitative approaches. Typical case sampling was used in the study and 30 fourth grade students from 11 different schools in Ankara were included in the study. Fake news and semi-structured interview form prepared by the researcher were used as data collection tools. During the implementation phase, the students were shown fake news and asked whether this was true or not. Afterward, interviews were made using the Socratic inquiry method over the comments created by the researcher. Six elements of thinking developed by Paul and Elder (2013) on critical thinking approach [(a) knowledge, data and experience, b) concept, c) perspective d) assumption e) inference, f) implicit inferences and results] used. During the data analysis, the codes were reached in line with the research problems, and the themes were reached by finding common aspects between the emerging codes, that is, by collecting them under categories. In this study, the data were subjected to content analysis by two researchers independently and the consistency between researchers was calculated as 87.5%. As a result of this study, it was determined that 92% of the expressions of primary school fourth-grade students were in the weak critical thinker category.