2.3. Procedure

This research was approved by the Bioethical Research Committee of the National Distance Education University (UNED, Spain). This study is part of a larger longitudinal study on socioemotional development during preschool years. The principal of the participating school was informed of the purpose of the study by the research team. Parents signed the appropriate consent forms. Teachers completed questionnaires after receiving information from the research team. They had 10–15 days to return the completed questionnaire. Both the university and the school followed the protocols for applying the ethical procedures that regulate research in Spain.