We invited a specialist in sustainability from ONG Mare Nostrum, an environmental organization, to our school, who came along with a volunteer. They spoke to our students about what each of us can do on a daily basis for living a sustainable life. They gave students a lot of examples of how we should choose carefully the products we buy, some samples of litter taken from the beach, in order to make our students aware of how they should not proceed, they taught them what sustainability is about. Then, our students found out what the carbon footprint is and how it can be calculated both for people and for a product.