This study investigated the effectiveness of LOGO's turtle graphics in both providing a model of systematic thought and in teaching simple geometry to young children in the second grade. The treatment given to 25 second grade students in the experimental group consisted of programming with LOGO's turtle graphics using four Apple II+ microcomputers. Students received approximately 1 hour of exposure every week for 3 months. The control group was a second grade class of 22 students from another school. Both groups were in the same school district and used the same textbooks and curriculum. The pretest and posttest scores of both groups were analyzed using dependent t-tests. The results showed that LOGO had a statistically significant effect on students' ability to think systematically and to understand certain geometric concepts. Nineteen references are listed. (Author/LMM)