This article focuses on the tensions created in teachers' activity by the uses of a symbolic instrumentan inquiry-based method called the Education Through Research model-and a digital one-the Student-Researcher Digital Notebook, designed to implement the model. Our research was guided by the following questions: How did teachers use these instruments to conduct their own class project and achieve their learning objectives? What kind of contradictions did the introduction of these resources lead to, and how did teachers try to overcome them? We collected data on the instruments and their uses through document analysis, interviews with the teachers as well as observations carried out in the classrooms. We analyzed data using Engeström's activity theory framework (1987) in order to understand the contradictions within teachers' activity created by the introduction of each instrument. Our main results indicate that both the ETR model and the SRDN first tend to disturb teachers' activity but then allow them to either carry out and change their practices or legitimate their pre-existing practices.