This pedagogical booklet is the result of the lessons learned from a 5-year project, between 2013 and 2018, with 50 elementary schools in the Marakanam block, in the state of Tamil Nadu in South India: the Bio-schools project led by SOL in partnership with Solidarité India. This project was born from the observation that one of the most restrictive barriers to changing lifestyles comes from the promotion of an intensive economic growth model at the expense of the environment.