The purposes of the study were to analyse the promotion of scientific literacy through practical research activities and to identify children's conceptions about scientists and how they do science. Elementary school children were engaged in two scientific experiments in a marine biology research laboratory. A total of 136 students answered a questionnaire about their previous habits towards science and carried out the following actions: (1) a guided visit to the laboratory, (2) a brief presentation of the research theme, (3) the development of two experiments, and (4) a questionnaire about the experiments and science conceptions. The research methods included observation, document analysis, and content analysis of the answers to the questionnaires. Additionally, each visit was video recorded in order to design learning materials. The results revealed that most of the pupils were able to follow every stage of experimentation. However, some of them misinterpreted results and conclusions. One implication of the study is that this type of outdoor activity is extremely important to promote meaningful science learning in children, but more care should be taken in practical science activities so that children can overcome some common difficulties when performing scientific inquiry. (Contains 1 figure and 3 tables.)