Teaching science is a challenge for teachers, as they face multiple needs that they often cannot solve. Fortunately, today they feel the need to train and become researchers of their own pedagogical practice, leaving aside traditional teaching, where the teacher instilled knowledge in his student and this was a passive actor in the learning process. For this reason, this research seeks to improve didactic processes and promote critical thinking in students. For this purpose, the theme of metacognition was chosen in the teaching-learning process of Mendelian genetics, seeking for the student to be autonomous and become aware of their own learning processes. In this regard, Tamayo (2006) says: “Metacognition is especially important for education and for science didactics because it affects the acquisition, understanding, retention and application of what is learned; its influence also occurs on the effectiveness of learning, critical thinking and problem solving ”(p. 275).