Although "Reproduction, Growth, and Development in Living Things" (RGDLT) is a core topic in the Turkish science curriculum, it is known that students have difficulties in understanding. Integrating concept cartoons and argumentation into the teaching of this unit has the potential to promote students' interest and understanding. This research is the first to compare the effects of concept cartoons and argumentation-based concept cartoons on students' academic achievement in teaching sixth grade RGDLT subjects. The research was performed with two experimental groups and one control group in a secondary school in Turkey. A quasi-experimental research design was used in the research. Analysis of the post-test results revealed that the success of the group using concept cartoons was higher than the control group, but more importantly, the success of the group using argumentation-based concept cartoons was higher than the group using concept cartoons. The results of this research indicate that the academic achievement of students can be increased significantly when concept cartoons and argumentation-based concept cartoon activities are used in addition to the constructivist methods in teaching these subjects. The results of the research serve as a guide for teachers and researchers interested in teaching science and biology subjects.