Der and have boarding facilities. Between 50 and 95 of students reside at the schools, which have separate dormitories and sanitary installations for boys and girls. One Isorhamnetin web school had a particular religious affiliation (school 3: Muslim). In another, which was later excluded, the mailbox technique was not correctly implemented (Table 1). The secondary-education order Isorhamnetin system in Rwanda is divided into two parts. In lower secondary, the first three years, students all follow the same programme. During higher-secondary education, the final three years, different study sections are offered. The age of the students in secondary education ranges from 12 to 30 years and even older. The median age of students in the last year of secondary education in the schools included in this study is 21 years (IQR of all students in the six schools ?17 ?20 years).Originally, we intended to use a diary method, in which young people could write about their experiences and thoughts concerning sexuality or relational issues over a certain period. However, as the majority of secondary-school pupils in Rwanda attend boarding schools where there are no safe spaces to store personal writings, privacy could not be guaranteed. Therefore, we sought a way in which young people could freely and voluntarily express their ideas on paper in a secure and private setting. The idea of a mailbox emerged, which offered the advantages of anonymity and spontaneity. Six secondary schools were given a mailbox and asked to install it in a place with a large passage of students, away from signs of authority such as the principal’s office. The mailboxes were locked and the keys kept by the principal investigator. Instructions were attached to the mailbox and the students received detailed information on the objectives of the study in a school assembly. It was emphasized that only the researchers would read the letters and that participation was voluntary. The following instructions were placed on the mailbox (translated into the local language Kinyarwanda): What’s your story? To better inform young people about relationships and sexuality, we must understand what they really think about these issues. What are your experiences with relationships and sexuality and what are your ideas, secrets, wishes, desires, fears . . . on these topics? In order to share your stories and ideas anonymously, we invite you to write them and then post them in this mailbox. We will collect the letters on [date specified]. We thank you for your story! This message was followed by practical information, such as telling the students they could write in any language and on any topic concerning sexuality. The information was also circulated via a letter to the students. Mailboxes were given to the six schools in March 2009. When returning to the schools three months later, we found that two schools had not installed the mailbox; in another school the lock had been stolen. The three other schools did hang the boxes, but on two of them the instructions had disappeared. We collected 25 letters, of which 14 letters had low relevance describing complaints about internal school issues, such as canteen food. After analysing the remaining letters and discussing the poor results, it was decided to reattempt the study. In SeptemberTable 1.Participating schools.Boarding school or not Boarding school Education offered Lower- and highersecondary education Lowersecondary education Highersecondary education Lower- and highersecondar.Der and have boarding facilities. Between 50 and 95 of students reside at the schools, which have separate dormitories and sanitary installations for boys and girls. One school had a particular religious affiliation (school 3: Muslim). In another, which was later excluded, the mailbox technique was not correctly implemented (Table 1). The secondary-education system in Rwanda is divided into two parts. In lower secondary, the first three years, students all follow the same programme. During higher-secondary education, the final three years, different study sections are offered. The age of the students in secondary education ranges from 12 to 30 years and even older. The median age of students in the last year of secondary education in the schools included in this study is 21 years (IQR of all students in the six schools ?17 ?20 years).Originally, we intended to use a diary method, in which young people could write about their experiences and thoughts concerning sexuality or relational issues over a certain period. However, as the majority of secondary-school pupils in Rwanda attend boarding schools where there are no safe spaces to store personal writings, privacy could not be guaranteed. Therefore, we sought a way in which young people could freely and voluntarily express their ideas on paper in a secure and private setting. The idea of a mailbox emerged, which offered the advantages of anonymity and spontaneity. Six secondary schools were given a mailbox and asked to install it in a place with a large passage of students, away from signs of authority such as the principal’s office. The mailboxes were locked and the keys kept by the principal investigator. Instructions were attached to the mailbox and the students received detailed information on the objectives of the study in a school assembly. It was emphasized that only the researchers would read the letters and that participation was voluntary. The following instructions were placed on the mailbox (translated into the local language Kinyarwanda): What’s your story? To better inform young people about relationships and sexuality, we must understand what they really think about these issues. What are your experiences with relationships and sexuality and what are your ideas, secrets, wishes, desires, fears . . . on these topics? In order to share your stories and ideas anonymously, we invite you to write them and then post them in this mailbox. We will collect the letters on [date specified]. We thank you for your story! This message was followed by practical information, such as telling the students they could write in any language and on any topic concerning sexuality. The information was also circulated via a letter to the students. Mailboxes were given to the six schools in March 2009. When returning to the schools three months later, we found that two schools had not installed the mailbox; in another school the lock had been stolen. The three other schools did hang the boxes, but on two of them the instructions had disappeared. We collected 25 letters, of which 14 letters had low relevance describing complaints about internal school issues, such as canteen food. After analysing the remaining letters and discussing the poor results, it was decided to reattempt the study. In SeptemberTable 1.Participating schools.Boarding school or not Boarding school Education offered Lower- and highersecondary education Lowersecondary education Highersecondary education Lower- and highersecondar.