In order to utilize the results of genetic tests for mental and behavioral changes aimed at disease prevention, it is important to acquire the right knowledge about genetic information. Learning the basics of genetic testing and information at school may help in taking adequate precautions against illness. In this study, to improve the knowledge on central dogma (flow of genetic information) and mutation, which are the basics of genetic testing, among children in the upper grades of elementary school, we devised an illustrative video and conducted educational activities through a test-linked illustrative video lecture (TLIV lecture). In addition, the degree of comprehension and the effectiveness of the TLIV lecture were evaluated using tests conducted before and after the lecture. Both fifth and sixth graders showed a low level of comprehension (50 points or less) before the lecture. On performing the same test after the TLIV lecture, both groups showed a high degree of understanding (65 points or more), a significant increase. From the above results, it was shown that the TLIV lecture that we devised could be used as an effective tool for improving knowledge on the above-mentioned content for fifth graders and above.