Nearly half of Bangladeshi girls reach menarche without knowledge of menstruation and many fear seeking support due to pervasive menstrual stigma. We aimed to explore the types of menstruation-related information and support adolescent female and male students want but may be uncomfortable verbalising. We installed a locked box in four school classrooms in rural and urban Bangladesh as part of a menstrual hygiene management pilot intervention between August 2017 and April 2018. Trained teachers provided puberty education to female and male students in classes 5–10 (ages 10–17 years) and encouraged students to submit questions anonymously to the boxes if they did not want to ask aloud. We conducted a content analysis of the 374 menstruation-related questions from a total of 834 submissions. Questions regarded experiences of menstrual bleeding (35%); menstrual symptoms and management (32%); menstrual physiology (19%); behavioural prescriptions and proscriptions (6%); concerns over vaginal discharge (4%); and menstrual stigma, fear, and social support (4%). Students wanted to understand the underlying causes of various menstrual experiences, and concern over whether particular experiences are indicative of health problems was pervasive. Ensuring comprehensive school-based menstruation education and strengthening engagement among schools, parents, and healthcare providers is important for improving access to reliable menstrual health information and may relieve adolescents’ concerns over whether their menstrual experiences are ’normal’