This research was financially supported by the Ministerio de Economía y Competitividad, Spanish Government (MINECO/FEDER, UE), References: PSI2015-67441-R and PSI2015-65766-R. We thank the schools and teachers who were involved in the project for their participation.
L. López-Romero and B. Molinuevo contributed equally to this work. The authors declare no conflicts of interest.