The purpose of the study is to determine the effects of using writing activities with different learning purposes by the secondary school 7th grade students on their academic achievement and attitudes towards the course. The study was carried out in a secondary school located in the centre of Erzurum in 2012-2013 academic year; the study is a quasi-experimental with pre-test-post-test design. 97 students from 3 classrooms formed the sampling of the study. These classes were divided into three groups randomly: letter writing, journal writing and control groups. This study was conducted with the 7th grade force and motion subject such as introduction to springs, labour and energy, simple machines, energy and friction force. Before starting the force and motion unit, all the students in the groups took achievement test and attitude pre-test; five-week teaching time was spared for force and motion subject. The participating science teachers taught force unit to all 3 classes by using the same instructional material and pedagogical approaches. Equal time on each task was provided for both groups. Upon completion of final version of the writing assignment post-test was implemented. The analysis of data revealed that journal writing group is more successful than letter writing and control groups. Also letter writing group is more successful than control group statistically. On the other hand, it was found that attitude towards science and technology course did not show a statistically significant difference according to groups.