Table 2. Pilot study tasks.

Tasks	Participants	Activities
1. Establishment of the IHC-Barcelona Working Group
1.1. Establishment of the coordination group	- Researchers	Group responsible for planning, coordinating and monitoring the different steps of the pilot study.
1.2. Establishment of the advisory group	- Researchers - Teachers - Paediatricians - Student representatives - Family representatives - Education and health stakeholders - Translators	Group responsible for reviewing and advising during the development of the different steps of the pilot study.
2. Protocol development
2.1. Protocol development	- IHC-Barcelona Working Group	Develop and publish the pilot study protocol. Request the approval of Ethics Committee of the Hospital de la Santa Creu i Sant Pau (Barcelona, Spain).
3. Preparation of the activities in the schools
3.1. Selection of the schools	- Coordination group	Select three schools in Barcelona (convenience sample).
3.2. Selection of the students and the teachers	- Coordination group	Select 4 th and 5 th-year primary school students (10 to 11-year-olds) and teachers.
3.3. Introduction of the pilot study to the families	- Researchers - Teachers	Introduce the IHC project and the pilot study in a meeting with the families (first meeting of the school year and/or specific meeting about the project).
3.4. Compilation of the informed consent forms	- Teachers	Request the families and the teachers to give their informed consent (Extended data 1, 2 and 3) 31.
3.5. Delivery IHC resources to the schools	- Coordination group	Send a book for each student. Send a book, a teachers’ guide, activity cards, and a poster for each teacher.
4. Intervention in the schools
4.1. Workshop with the teachers	- Researchers - Teachers	Introduce and review the IHC project, the pilot study, and the IHC resources with the teachers (Extended data 5) 31.
4.2. Lessons to the students	- Students - Teachers	Teach students to assess treatment claims and make informed health choices using the IHC resources.
5. Data collection
5.1. Assessment of the IHC resources by the teachers before the lessons	- Teachers	Explore the teachers’ initial perception of the IHC resources (Extended data 6) 31.
5.2. Non-participatory observations during the lessons	- Researchers	Assess (objectively) the degree of implementation of the IHC resources and explore the students’ experience when using the IHC resources (Extended data 7) 31.
5.3. Semi-structured interviews with the students after a lesson	- Students - Researchers - Teachers	Explore the students’ experience when using the IHC resources (Extended data 8) 31.
5.4. Assessment of the lessons by the teachers after a lesson	- Teachers	Assess (self-reportedly) the degree of implementation of the IHC resources and explore the teachers’ experience when using the resources (Extended data 9) 31.
5.5. Treatment claim assessment by the students at the end of the lessons	- Students	Evaluate the ability of the students to assess treatment claims and make informed health choices after using the IHC resources in this context (the questionnaire is accessible upon request from the Testing Treatments website to preserve the validity of the questions).
5.6. Assessment of the IHC resources by the teachers at the end of the lessons	- Teachers	Explore the teachers’ final experience when using the IHC resources and compare their initial perception with the final experience (Extended data 10) 31.
6. Data analysis
6.1. Data analysis	- Researchers	Quantitative and qualitative analysis of the data.
7. Formulation of the recommendations
7.1. Formulation of the recommendations	- IHC-Barcelona Working Group	Suggest and agree some recommendations on how to implement the IHC resources in this context.
8. Dissemination of the results
8.1. Dissemination of the results	- IHC-Barcelona Working Group	Publish in a peer-reviewed journal, publish in several internet resources and introduce to the different users of interest.