The article addresses two important subjects (observer training and school violence) and could serve as a relevant guide for for the methodic implementation of training programs for "observers of school violence".
However, there are two major shortcomings that will required substantial re-writing: 1) one of formal presentation and organization of the article and 2) another of (scientific) focus of the article.
1) The article is not presented in a normative article layout (e.g. Abstract, Introduction, Methods, Results, Discussion, Conclusion), which is very confusing to read and to fully understand the information. In addition, the vast majority of the article references were published more than 5 years ago, which pertains to the validity and relevance of the constructs and state-of-the-art of the research project itself. 
2) It is not clear if the authors intend to a) focus on the participatory research aspects (such as the observer's' perspective on the research), b) instrument validation-related aspects or c) the results of the observation on school violence. This tri-fold confusion leads to a mismatch between the proposed objectives, the presented information and the study conclusions.