The paper describes an evaluation study of education for sustainability activities on agroecology promoted by the environment department from the city of Sant Cugat del Vallès. The methodology used in the evaluation study is based on the development of focus group during lunch time in a public space. The participants in the focus group are the environmental educators responsible for the activity, a sample of teachers responsible for the group of students, the representative from the city hall, and the researcher. Previous to the focus group activities have been observed and video recorded to prepare a video clip to be used during the development of the focus group to prompt participation. Data has been categorized in terms of the content (evaluation statements, and proposals for action), as well as in terms of actors (Environmental educators and teachers). Results have been very positive since proposals for the improvement of activities have been negotiated with consensus and they have been implemented during the academic year 2010-11. The study has provide evidence that focus group implemented in this way can be a very powerful tool to build a space for participation and encounter between teachers and environmental educators and to build a join perspective on education for sustainability on schools