Research has shown that teachers prefer authority-based interventions towards bullies but seem to neglect to support the victims. Unfortunately, teacher training curricula tend not to include preventive and interventive skills regarding school violence. It has been shown that teachers who set limits and make it clear that previous behavior is in no way acceptable, and also involve the school administration, can reduce problematic behavior. Discussing the issue with the entire class can also lead to positive preventive effects. Not only does physical violence in schools affect its victims, it also affects the witnesses. In elementary schools, young students tend to copy their peers actions in schools, which may lead to more physical harm towards other students. Some intervention programs are aimed at improving family relationships. There is some evidence that such intervention strategies have modest effects on the behavior of children in the short and long term. Patterson's home intervention program involving mothers has been shown to reduce aggressive conduct in children. An important question concerns the extent to which the influence of the program carries over into the child's conduct in school. Some prevention and intervention programs focus on individual-level strategies. These programs are aimed at students who exhibit aggression and violent behaviors or are at risk for engaging in such behaviors. Some programs include conflict resolution and team problem-solving. Other programs teach students social skills. The Conduct Problems Prevention Research Group, while developing and implementing a universal anti-aggression component for all elementary school children, also developed and implemented a separate social-skills and academic tutoring component that targets children who are the most at risk for engaging in aggressive behavior. Bullying prevention programs such as Olweus provides materials for educators that will train them on how to mediate a bullying situation as well as procedures to take if a child is suicidal. Challenges in measuring violence in schools Research on violence affecting children in schools is challenging for a variety of reasons. Methodological issues When trying to measure the scope of violence in schools and to find out about the types of violence experienced by students, some key issues include: from what categories of the school community to collect the data; what data should be collected from each categories; and using which methods. For example, should there be studies or surveys where researchers ask students directly about violence in school, through self-reports about the violence they experienced as targets