Objectives: understand how we determine abnormality, understand key factors in understanding abnormality with children and youth. Overview: abnormal behaviour in children, defining abnormality, abnormality vs diagnosis, key factors for children. 2017 drug use among ontario students 1977-2017: detailed findings from the ontario student drug use and health survey (osduhs). Historical views and breakthroughs: early writings suggest that children were considered servants of the state in the city-states of early. The public generally distrusted and scorned anyone who appeared mad or possessed by the devil or similar evil forces. In 1909, clifford beers, a layperson who had recovered from a severe psychosis, spearheaded efforts to change the plight of others also afflicted. John watson (1878-1958) is known for his theory of emotions, which he extrapolated from normal to abnormal behavior. The therapy was originally based on operant and classical conditioning principles established through laboratory work with animals.