This research seeks to develop a critical reflection that frames, characterizes and evaluates the homework as a teaching strategy in the curricular area of "Environment Study" in the Portuguese primary education. For that, we considered three dimensions: the type of methodology used; the number of homework assignments; the duration of the assignment by the student according to the time provided by the teacher. For methodologic purposes, we followed the case study method as we wanted to investigate the homework during a definite period in a narrative and profound way. An original instrument, called "Homework Data Collection", was created to answer the three research questions. The results show that there isn't a preferred homework methodology. We found also a lack of proportionality between work time and study hours of "Environmental Study". About the time taken by students to perform homework, we found that teachers are very well prepared to predict the time students take.