This study aimed to determine STEM practices assisted by argumentation-based learning, the attitudes and the opinions of the students towards STEM, their perception of problem-solving skills and the argumentation qualifications. In the research, the mixed design has been implemented. The quasi-experimental design with pre-test and post-test control group has been conducted in the quantitative dimension. The research group consists of 55 students--studying at a state school affiliated to Mus Provincial Directorate of National Education. In the study, the qualitative data were collected using 'STEM attitude scale' and 'problem solving skill perception scale'; and the quantitative data were obtained using 'STEM interview form' and 'Written Argumentation Form'. The results show STEM practices have been observed to be effective in improving the attitudes of the students towards STEM and their problem-solving skills. Also, the opinions of the students are positive and the argumentation qualities of the students are at the first level during the practices.