The purpose of the study was to evaluate the impact of an HIV / AIDS module, taught for 24 hours over eight weeks in six schools, on the knowledge and attitudes of Grade 11 biology learners. The module contained scientific content on HIV / AIDS and outcomes-based assessment activities. Learners' answers in pre-, post- and retention tests and a questionnaire that included open and closed questions on general and functional knowledge, attitudes and skills (analysed for significant changes). Narratives written by each learner were analysed to determine how the module had dealt with issues that affected their lives. Analysis of the tests and questionnaires showed a significant improvement in the means scored in the pre-, post- and retention tests. ANOVA showed that the difference was unlikely to be attributable to chance. Narrative analysis identified a number of common themes. The learners were glad to have been taught this information and many provided evidence of how the module impacted on their lives and sexual behaviour. They felt the knowledge had empowered and motivated them to control their own lives.