We evaluated three aspects of an environmental education (EE) process: relationship between level of knowledge and level of interest in the conservation of biodiversity, EE efficiency in activities in situ versus ex situ in nature and relationship between level of personal involvement and increase in knowledge-interest in conservation. For this, high school students from a public school in the RN were divided in groups with different levels of participation (high, medium and low) on activities carried out in situ and ex situ in nature. We observe the direct relationship between level of knowledge and level of interest for nature conservation. We found that practical activities with or without the presence of the natural environment were effective for EE; however, the activities in situ were more effective. Finally, students with higher levels of participation in the proposed activities were more stimulated by the action.