Engineering education includes both theory and practice aspects. Laboratory courses are commonly used to provide the students with the required practical knowledge on the manipulation of materials, energy, information, etc. that will be the basis of their future professional activities. However, the effectiveness of laboratory courses could be significantly improved by a better understanding of the learning objectives by the students. In this work, the utilization of conceptual maps is proposed as a means to enhance the effectiveness of practical teaching in engineering studies. Concept maps are graphical tools for organizing and representing knowledge, which include concepts, usually enclosed in circles or boxes, and relationships between concepts indicated by a connecting line. The students are provided with basic information on the laboratory activity they are going to perform, and then required to construct conceptual maps representing said activity, with especial focus on its main objectives and stages. This can be carried out as an individual or group assignment, but in all cases the maps are compared and discussed before starting the actual lab work. An environmental engineering course is taken as example of the application of this strategy.