“…From that point of view, following O'Leary's (2012, p. 865) reading of Ted Wragg's classic introduction to the topic, observation "becomes part of a 'collection of data', thus recognising that it is one of several sources of evidence in the formal appraisal process". Epistemologically speaking, such an argument elaborates upon the complexities of the structure and agency debate in educational research (Clegg, 2005;Parra, 2017) and against the theoretical determinism that validates the teacher effectiveness -as a single and universal determinant -stand in the debate. O'Leary (2012, p. 808) presents such a dilemma in the following way:…”