Our main goal in this study was to determine whether the use of computer animation and illustration activities in high school can contribute to student achievement in molecular genetics. Three comparable groups of eleventh- and twelfth-grade students participated: the control group (116 students) was taught in the traditional lecture format, whereas the experimental groups received instructions that integrated a computer animation (61 students) or illustration (71 students) activities. We used three research instruments: a multiple-choice questionnaire; an open-ended, written questionnaire; and personal interviews. Five of the multiple-choice questions were also given to students before they received their genetics instruction (pretest). We found that students who participate in the experimental groups improved their knowledge in molecular genetics compared with the control group. However, the open-ended questions revealed that the computer animation activity was significantly more effective than the illustration activity. On the basis of these findings, we conclude that it is advisable to use computer animations in molecular genetics, especially when teaching about dynamic processes; however, engaging students in illustration activities can still improve their achievement in comparison to traditional instruction. (Contains 2 figures and 3 tables.)