The activity uses drawings typically found in textbooks, engaging students in physical and mental activities such as drawing, painting and figure completion--as well as finding missing words and answering guiding questions. The activity deals with three topics: the structure of DNA, DNA replication and protein synthesis. In this study we investigated students' understanding of genetics in two different groups: one used the drawing-based activity integrated in the traditional learning (experimental group) and the other, the control group, received only traditional learning. Achievements of the experimental group were compared to the achievements of the control group, using a written questionnaire. Analysis of the post-test showed that the mean score of the experimental group was significantly higher than the mean score of the control group, suggesting that engaging students in physical and mental activities promote students' learning. This positive trend was also reflected in students' responses in personal interviews. Most of the students reported they felt that the activity helped them to organise and better understand the subject matter, especially the translation process. (Contains 3 figures and 2 tables.)