Introduction: The main Objective of the Informed Health Choices (IHC) project is to teach people to assess treatment claims and make informed health choices. For this purpose, the IHC learning resources were developed for primary school children. The aim of this study is to explore students’ and teachers’ experiences when using the IHC resources in Barcelona (Spain) primary schools. Methods: We conducted a mixed method study for piloting the IHC resources in Barcelona (Spain) primary schools. The intervention included a workshop with teachers and family members, and nine lessons with the students. We collected data using multiple approaches, including ad hoc questionnaires, non-participatory observations, and semi-structured interviews. We performed quantitative and qualitative thematic analyses to explore understandability, desirability, suitability, usefulness, and facilitators and barriers for using the IHC resources. Results: Two schools with a total of 143 students in 4th and 5th grade (9 to 11-year-olds) and six teachers participated in the study. One school competed all the lessons and followed the suggested IHC teaching plan. The other school did not complete all the lessons and changed the teaching plan substantially. Overall, students and teachers understood, were interested, and were able to apply the content of the lessons. During the lessons, students used the IHC resources (mainly the textbook), but teachers used them in a variable way. Teachers adapted the IHC resources to promote increased student participation and used Information and Communications Technologies to support their teaching. We observed more facilitators than barriers to teach the lessons. Teachers suggested some ideas to improve the lessons based on the activities they developed and implemented. Conclusions: It is feasible to use the IHC resources in Barcelona primary schools. However, the IHC resources should be adapted for this setting to increase students’ participation in classroom.