Teachers receive two sets of activities, accompanied by a tutorial. Both sets of activities also include evaluation tools that teachers can use to clarify the objectives of the lesson and to assess the pupils' learning progress. The estimated length of each set is 5 hours.The activities and the tutorials were created by pedagogical experts of the Fondation La Main à la pâte, an NGO whose goal is to foster science education. Activities and tutorials are now freely available on the La Main a la pâte website. Teachers were free to choose whether to present the first or the second set of activities, and to choose how many of the activities to conduct. The actual length of the intervention thus varied from one classroom to another, which mimics ecological conditions. Teachers were asked to devote at least one hour to the activities.

LAMAP activities are available on the experiment's OSF repository

Teachers, and then pupils, receive a link to a chatbot. This chatbot is a basic conversational agent that can answer the most common questions about vaccination. The chatbot is entirely scripted, providing users with a limited choice of questions at each stage. These questions are the most commonly raised questions about vaccination in adolescents, based on existing literature, and on focus groups conducted by our team. In this intervention, teachers will be asked to supervise the use of the chatbot in class. Pupils will use the chatbot either individually or in groups depending on the number of computers available. Teachers will be encouraged to conclude the intervention by a class discussion. Teachers will be asked to devote about one hour to this intervention (use of the chatbot and class discussion). The full chatbot text is available on the experiment's OSF repository

Two activities created by the La Main a la Pate foundation

Participants' attitude towards vaccination were measured as the average agreement with 4 questions measured on a 7-points Likert Scale created for this study, ranging from 1 - "Completely disagree" to 7 - "Totally agree", where a higher score corresponds to more positive attitudes towards vaccination.

"The vaccines used in France are effective" "The vaccines used in France are safe" "Vaccines are useful because they protect us from dangerous diseases". "It is important to get vaccinated to protect others". For the full questionnaire, see the experiment's OSF repository.

All outcomes were assessed three times: before teachers received our interventions (November 15th - December 12th), in the middle of the school year (March 6th -June 8th), and after all teachers used our interventions (May 11th - June 23rd).

Knowledge is measured as the average number of correct answers to 11 True or False questions:

"Vaccines are not necessary, since diseases can be treated by drugs (such as antibiotics)" "Without vaccines, smallpox would still exist" "The effectiveness of vaccines has been scientifically proven" "Children would be more resistant if they did not receive so many vaccines" "Vaccination can cause certain disorders, such as autism, multiple sclerosis or diabetes" "If a child receives too many vaccines at once, it can overload their immune system" "The chemicals included in vaccines are not dangerous" "Vaccination increases the risk of developing allergies" "Vaccines are injected too early, which prevents children from building their immune systems" "Vaccines cannot cause the disease they protect against" "Thanks to scientific advances, scientists can create vaccines with fewer side effects"

Like all other outcomes, knowledge was assessed three times during the year.