The objective of the present study was to apply the Flipped Classroom Methodology (FCM) to teach Genetics in the senior year of a public high school, and to evaluate its effectiveness according to the performance of its students. Two didactic sequences were applied: one called Traditional Classroom (TC) and the other Flipped Classroom (FC). The students who were taught through FC dedicated more time to their studies, presenting greater ease to learn the contents. Some reported difficulty managing study time due to balancing study and work, and they had significantly higher scores than the students of the TC. We concluded that the FCM is effective in teaching genetics. However, the reality of many high school students from public schools includes the need to work to complement the family income, which can become an obstacle for the students' full development and motivation through this methodology.