The purpose of this study was to determine the effect of writing science notebooks on learners' academic achievement, scientific process skills and retention levels in the fourth grade science classes of elementary school. For this purpose, quasi-experimental design was used in this research. The study was conducted with the students of 4/A and 4/C classes of a primary school which is located in the center of Eskisehir city and the study lasted for eight weeks. The data of the study were collected through Achievement Test and Scientific process skills Scale. The data were analyzed through Wilcoxon and Mann Whitney U tests both of which are non-parametric tests. Results of the study showed that keeping a science notebook had positive effect on academic achievement, scientific process skills and retention skills of the students in experimental group.