In order to teach the phases of cardiac cycle for students from Dental School we developed a puzzle, with one table of 5 columns: 1. Phase of cardiac cycle, 2. Atrial state, 3. Ventricular state, 4. Atrio ventricular valves and 5. Pulmonary and aortic valves, painted in different colors: white, blue, green, yellow and pink, respectively. Figures of the phases of cardiac cycle and colored chips are also provided to be used in order to complete the table. White chips indicate the names of the cardiac cycle phases. Blue and green chips present the options relaxed or contracting. Open or closed is written in the yellow and pink chips. The students (in groups) are invited to analyze the figures and to complete the the table with the chips. During the activity the professors discuss with them why they choose each chip. Also the following questions are presented to the students during the activity: When and how do the cardiac valves open and close? How is the electrical stimulus transmitted through the heart during each phase? How do the gap junctions participate in the conduction of cardiac electrical stimulus? Which is the role of atrioventricular delay of action potential in the cardiac cycle? In recent years, using this puzzle, teachers have noticed that students more easily establish the relationship between the morphological characteristics of cardiac muscle with the cardiac cycle, compared with the lecture on the subject.