Aims: The aim of this study was to compare the effect of different educational methods of tooth brushing (lecture, video and pamphlet) on dental plaque index of 12 year-old children. Design: A cluster randomized not blinded interventional trial was performed in January to April 2017 on 128 children aged 12years in public and private schools of Babol city (north of Iran). The participants were randomly allocated into four groups based on the type of intervention; group 1: no intervention, group 2, 3, 4: education via lecture, video and pamphlet, respectively (n=32). Method: Plaque index (PI) was determined by oral examination at the baseline and 2 month later for group1. Also it was recorded before education and 24 hours, 1 and 2 months later for groups 2, 3, 4. Participants: Healthy children who had the teeth # 11, 16, 26, 31, 36, and 46 were included and who were dissatisfied to participate in the study or had physical and mental problems that limited learning ability, had a painful tooth in the mouth or sensitivity to toothpaste and a large dental calculus were excluded. Interventions: Education of tooth brushing via lecture, video and pamphlet. Outcome: Plaque index before and after the education.