Environmental education in the 21st century requires well-instructed teachers with teaching and communication abilities. This paper presents an educational experience developed in several biology and environmental teacher training courses and focused on the treatment of environmental education as a transversal educational topic. For that aim, text analysis techniques, concept mapping and informatics tools have been used to represent individual and collaborative knowledge about environmental topics. 69 students participated in the research. Data about the educational activities developed by the participants have been collected. Furthermore, students have expressed their opinions on the formative process by means of an opinion survey. The outcomes of this study reveal that future teachers and environmental educators consider that concept mapping is a valuable tool to represent their knowledge about environmental education, to encourage reflexive and collaborative learning, to improve teaching communicative abilities and to use effectively ICT in the classroom.