The aim of this study is to evaluate mathematics lessons based on writing activities. The study was conducted during the 2004-2005 spring term in a 6th grade class with students over a ten week period. Lessons were given by the teacher researher using various writing activities in traditional teaching. The writing activities used in the study are (a) explanatory writing, (b) journals, (c) writing about a problem stuation based on a scenaria, (d) open-ended resposes to study expressions. The findings in the study were obtained using the following ways; examining students' writings, analysing students' written responses to a given scenario and using a qualitative anaiisis of the semi-structured interview with ten students. It is found that the mathematical communication increased in the classroom. Writing activities make concrete the abstract mathematical symbols and also help students to form positive attitudes towards mathematics and writing in general. Preservice and inservice courses must be presented teachers to encourage the use of writing activities more in mathematics lessons for improving of the productivity.