Constructivism is not a new concept. It has its roots in philosophy and has been applied to sociology and anthropology, as well as cognitive psychology and education. The aim of this research is to reveal if there is a significant difference between the means of achievement and retention learning scores of constructivist learning approach applied group and conventional training approach applied group. Since an experimental research was treated, no population or sampling group process was stated. In the research, the pupils of sixth class, studying in Yunus Emre Elementary School at city center of Eskisehir, in spring term of 2005-2006 academic year were chosen. Pre-test scores of experimental and control groups and the means of the scores of science lesson fall term of sixth class were evaluated and appropriate two classes were chosen. 6-A class was chosen as the experimental group and 6-B class was chosen as the control group at random. In this research, one of the experimental designs which provide quantitative data about the primary and secondary subproblems called "Pre-test, Post-Test with Control Group Design" were implemented. (Contains 4 tables.)