The informal activities of cooperative learning and short periods of lecturing has been combined and used in the university teaching of biochemistry as part of the first year course of Optics and Optometry in the academic years 2004-2005 and 2005-2006. The lessons were previously elaborated by the teacher and included all that is necessary to understand the topic (text, figures, graphics, diagrams, pictures, etc.). Additionally, a questionnaire was prepared for every chapter. All lessons contained three parts: objectives, approach and development, and the assessment of the topic. Team work, responsibility, and communication skills were some of the abilities developed with this new methodology. Students worked collaboratively in small groups of two or three following the teacher's instructions with short periods of lecturing that clarified misunderstood concepts. Homework was minimized. On comparing this combined methodology with the traditional one (only lecture), students were found to exhibit a higher satisfaction with the new method. They were more involved in the learning process and had a better attitude toward the subject. The use of this new methodology showed a significant increase in the mean score of the students' academic results. The rate of students who failed the subject was significantly inferior in comparison with those who failed in the previous years when only lecturing was applied. This combined methodology helped the teacher to observe the apprenticeship process of students better and to act as a facilitator in the process of building students' knowledge.Keywords: Biochemistry, cooperative learning, lecturing, collection of questions, work plan.Lecturing renders students passive, silent, isolated, and in competition with each other. The main disadvantage of lecturing is that students' attention decreases during the teacher's exposition. When the lecture is long, the first few minutes are good for assimilation, but confusion, boredom, and a low level of assimilation sets in later on [1]. In most cases, lecturing is a process in which information passes from the notes of the lecturer to the notes of the student without passing through their minds.Several strategies can be used to get student participation and active learning. Cooperative learning (CL) 1 is a method of instruction that involves students working in teams to accomplish a common goal [2], under conditions that include the following elements: positive interdependence, team members are obliged to rely on each other to achieve the goal; individual accountability, teammates are held accountable for their share of the work; face-to-face promotive interaction, group members provide feedback, teaching, and encouragement to each other; development of collaborative skills; and group processing, team members periodically assess what they are doing and propose changes to work more effectively in the future. CL is an extensively researched approach to education that increases students' learning of subject matter and improves their attitudes...