Everyone has an implicit notion about what it means to learn and there is a general consensus that learning comprises relatively permanent changes in mental structures that occur as a result of experience. When it comes to education, there is the preliminary task of negotiating the relationship between teaching and learning, since they are often mistakenly equated. The relationship between both teaching and learning processes can be seen as a process in which the first (teaching) is a means to achieve the second (learning). As they say, learning is what one does with experiences provided by teaching. The word learning comes from the Latin word which means to acquire knowledge of a subject or learn a skill through study or practice, after a long process or repetition. It is a permanent change of behavior, positive or negative, by experience, through new information. Learning is then the consequence of being taught, through exposure to stimuli, experiences, and suitable learning mechanisms. This chapter discusses learning mechanisms in science education. Learning mechanisms are the processes that allow students to participate in science education, helping them to construct, retain, and utilize knowledge, heuristic, and dispositions. Specifically, mechanisms describe how children learn through cognitive, intellectual, or neural processes. Learning mechanisms combine knowledge, cognitive dispositions, heuristic values, and expert-like exercise of learning. Learning mechanisms are distinctive because they are related to processes, not factors. Most theories describe sources of learning or specific cognitive traits associated with learning and their implications. It is proposed that the processes at the core of modular instruction are mechanisms, resulting from their choice and the development of supporting actions in activities. The description presented in the chapter seeks to provide future scholars and teachers an understanding of the role of learning mechanisms, clarify some specific concepts, and build links with other similar constructs. These mechanisms are pointers to how learning works in science education.