The Regional Ministry of Education will endorse the participation of each selected school in the study. At the beginning of the study, families of all children in the selected classes will receive an invitation to an initial meeting at school to receive information about the study. Both children and parents will be encouraged to participate in the study. Parents will sign an informed consent which include the participation of them and their child. The study protocol has been approved by the University of Granada Human Research EthicsCommittee (Reference: 57/CEIH/2015).