The effect of instructional tasks prepared based on interdisciplinary instructional approach on students' academic achievement in the subject of volumes of geometric objects and their problem solving skills.

The purpose of this study was to determine "the effect of instructional tasks prepared based on inter-disciplinary instructional approach on students' academic achievement in the subject of volumes of geometric objects and their problem solving skills". The study was conducted by "pre-test post-test control group model" and experimental method was used. The sample of the study was consisted of 8th grade students enrolled in IMKB middle school in Bartın in 2014-2015 academic year. There were totally 60 students, 30 in experimental group and 30 in control group participated in the study. The groups were determined according to cluster analysis. While in experimental group, lessons were taught by tasks prepared according to inter-disciplinary instructional approach for four weeks, in control group lessons were conducted by curriculum method. The lessons were taught by tasks interacting inter-disciplinary between courses science and technology, mathematics, technology design. The data of the study was handled by mathematics achievement test and problem solving skill scale developed by the researcher and their reliability and validity were satisfied. The data gathered resulting from implementation was analyzed by SPSS package program and during the analysis of data dependent and independent groups t-tests were conducted. According to the results of the study, it was founded that the inter-disciplinary approach positively affected the students' on volumes of geometric shapes academic achievement compared to the curriculum instruction but no significant effect on problem solving skill was revealed. Along this, it is recommended that in order to follow the development of problem solving skill, much longitudinal studies should be performed. Keywords: Inter-disciplinary, problem solving skill, volume, task.