The purpose of this research was to analyze the classroom use of the Science schoolbook in primary schools of the Municipal Department of Education of Rio de Janeiro. We sought to understand how teachers employ and evaluate the schoolbook and how it is incorporated into their teaching practice. The research has a qualitative nature, and the following methodological resources were employed: interviews, observation of Science classes, and questionnaires administered to students. The theoretical framework is based on studies on recent educational reforms influenced by neoliberal principles (Afonso, 2012; Ball, 2012; Freitas, 2014), debates on schoolbook-based teaching in Brazil (Adrião 2009; Marcondes, 2013), and reflections on current Science teaching trends (Carvalho, 2004; Krasilchick, 1992; Delizoicov, 2008). The conclusions of the research indicate that adopting the schoolbook influences the way of teaching Science. All teachers researched use the schoolbook as a guiding tool. Some use it as their single teaching resource, whereas others employ it along with complementary activities devised by themselves. In the schools researched, the use of the schoolbook as a guiding tool minimizes the development of the Political Pedagogical Project. Since the contents of the schoolbook are directly linked to the Bimonthly Examinations, what is asked in those exams determines what will be taught in class. The research also showed that since teachers acknowledge both advantages and limitations regarding the use of the schoolbook, their approach toward it is not passive; on the contrary, they make adjustments and adaptations to the their students reality.