A fundamental objective of environmental education (EE) and education for sustainable development (ESD) is the promotion of critical thinking, through which learners could resist messages (e.g., from TV), leading to unsustainable lifestyles and practices. The analysis of messages from media was used for: identifying influencing techniques; presenting these techniques to secondary school students allowing them to identify the techniques in messages from advertisements and assess their impact. After a very brief educational intervention, 84 per cent of the students were able to identify and decode techniques and make useful reflections. Furthermore, some techniques were tested as potentially useful for enhancing learning and/or environmental-friendly attitudes. The use of advertisement methods in teaching did not facilitate the assimilation of knowledge related to environmental science (chemistry); however, it improved the attitudes towards environmental-friendly and sustainable approaches.