The article explores the processes required for the observation and evaluation of teaching for formative purposes. In tandem, it critically approaches the overall context of teaching, namely the characteristics, factors, elements and particular aspects that affect the teacher observation we conducted, for formative assessment purposes, during a three-hour second grade Greek Language class. We focused on gathering remarks and suggestions that would assist the observed teacher in improving her teaching repertoire and practice, her overall professional development and, eventually, the improvement of the teaching process. We also enhanced our skills in teacher observation, formative assessment and reflecting thinking. The contemporary trends in teachers’ and teaching evaluation were also explored. Finally, critical reference is also made to the implementation processes of integrated teacher observation for formative assessment purposes, the methods, means and tools employed, the obstacles faced and the results of our feedback-oriented encounter with the observed teacher.