The effects of mind games in math and grammar courses on the achievements and perceived problem-solving skills of secondary school students Turgay Demirel and Turkan Karakus Yilmaz Turgay Demirel received his PhD at Computer Education and Instructional Technologies Department in Ataturk University. His research interests are game-based learning, blogs and instructional technology integration. Turkan Karakus Yilmaz is assistant professor at Computer Education and Instructional Technologies Department in Ataturk University. Her research interests are 3D virtual worlds, digital game-based learning and safer internet use. Address for correspondence: Dr Turgay Demirel, Computer Education and Instructional Technologies Department, Faculty of Education, Ataturk University, Turkey. Email: tdemirel@atauni.edu.tr Abstract The goal of this study is to determine the effectiveness of mind games played by secondary school sixth grade students as classroom activities in math and grammar courses on their perceived problem-solving skills and achievements. In the quantitative part of the study, the nonequivalent groups pre-test–post-test control group design from single-factor quasi experimental designs was used. Qualitative data collection and analysis approaches have also been used to support and explain quantitative data. The study’s sample group, which was formed using a convenience sampling method, consisted of 48 sixth grade secondary school students who studied in a moderately developed city center in Turkey and their teachers. An achievement test, perceived problem-solving skills scale and semistructured interview guide were used as the data collection tools. According to the findings, the students in the experimental group who played mind games showed development in their perceived problem-solving skills and achievements compared to the control group. The opinions of the teachers and students on the effects of the mental practices were also found to be positive. Introduction Today’s learners need specific skills, such as problem-solving, reasoning and critical thinking, to prepare for an increasingly complex life. However, the focus of educational trends in the 21st cen- tury has shifted toward “learning” from “teaching” (Goad, 2012). In this direction, education systems have been rearranged based on the constructivist approach, which is critical about gain- ing the above-mentioned skills, adopting a student-centered approach rather than a teacher- centered approach. This constructivist approach has emphasized the notion that learners form their own knowledge (Airasian & Walsh, 1997). Therefore, it is important to establish learning environments that focus on the students, in which the students are active, the thinking skills are taken into consideration, and that social interactions are supported (Brooks & Brooks, 1999). Games, which are suitable tools of the constructivist approach, seem to play an important role in the active participation of learners (Chen, Liao, Cheng, Yeh, & Chan, 2012). In the literature, games are reported to support various learning outcomes, such as visual and spatial skills (Bar- lett, Anderson, & Swing, 2009), problem-solving skills (Kiili, 2007), analogical reasoning (Williams, Ma, Feist, Richard, & Prejean, 2007) and learning of the subject matter (Papastergiou, V C 2018 British Educational Research Association British Journal of Educational Technology Vol 00 No 00 2018 00–00 doi:10.1111/bjet.12624