Research in New Zealand on secondary school students' experiences of bullying at school suggests that students and staff have different perceptions about the extent of bullying (Nairn & Smith, 2002). US research has also found differences between students' and parents' perceptions of behaviour, including weapon carrying (Young & Zimmerman, 1998) and substance use (Deffenbaugh, Hutchinson & Blankschen, 1993). In the Christchurch longitudinal study, students' reports of carrying a hidden weapon or using a weapon in a fight were considerably higher than parents' reports of their adolescents' behaviour (Horwood, 2007). These differences in perception of the extent of adolescent problem behaviour are not solely between adults and adolescents. A recent national study of principals' and counsellors' perceptions of physical aggression in New Zealand secondary schools found a lack of agreement in most areas related to aggression (Marsh et al., 2008a). These differences may explain why it is sometimes difficult for schools and parents to believe the results of self-report data on health-compromising behaviour, as was emphasised by the New Zealand media after the publication of findings relating to weapon carrying by high school students (McGee et al., 2005; Woodham, 2005).
Teachers have a critical role in efforts to reduce these types of risk behaviour; prevention strategies require the support of a number of key people, including teachers, if they are to be successful. If teachers are unaware of the kind and frequency of risk behaviour that adolescents are involved in, they may well be uninterested in efforts to reduce its prevalence. Consequently, it is important to know if teachers accurately perceive the extent of behavioural problems among students at their schools (Laufer & Harel, 2003; Orpinas, Murray & Kelder, 1999) but few studies have measured teachers' perceptions of adolescent risk behaviours (Price & Everett, 1997a).
Students are not the only victims of aggressive behaviour at school; aggression by students towards teaching staff also exists. In England in 2006/07, 1460 students were permanently excluded from state funded secondary schools for physical assaults or verbal abuse/threatening behaviour against an adult, while a further 90 330 students were excluded for a fixed time for these same reasons (Department for Children, Schools and Families, 2008). A US survey of schools and staffing found 7 per cent of participants had been threatened with injury, and 4 per cent had been physically attacked by a student at their school in the past 12 months (Dinkes et al., 2006). Australia reported between 55 and 450 incidents of violence, or assaults on school staff, in five of its states in 2000 (Colman, 2002). In New Zealand, teachers increasingly face physically aggressive behaviour in their workplace (Benefield, 2004). Nearly a third of all teachers experience minor forms of bullying on a daily or weekly basis, mostly from students. Eighty-five per cent reported less frequent but more significant bullying incidents within a school year. In 2004, 435 students were stood down and 155 were suspended for physical assaults on staff (Ministry of Education, 2005). This tense situation in schools may compromise the learning environment and contribute to severe psychological distress among teachers (Finlay-Jones, 1986).
The main aim of this study was to examine teachers' perceptions of physical aggression among New Zealand secondary school students. A second aim was to explore the influence of students' perceptions and behaviour on teachers' perceptions of physical aggression at their school. The term 'physical aggression' in our research reflects a variety of behaviour and was defined as 'deliberately harming another person, this could include: pushing; biting; fighting; shoving; kicking; hitting; burning; or threatening with or using a weapon', as used in the Dunedin Multidisciplinary Health and Development Study (Martin et al. …