Excessive exposure to solar ultraviolet (UV) radiation causes sunburn and has been consistently associated with increased susceptibility to melanoma and skin ageing. Acknowledging the need to promote healthy sun exposure habits, numerous educational initiatives have been developed to raise public awareness towards this issue. However, studies reveal that misinformed behaviours persist, particularly amongst young people, emphasising the need to broaden the range of interventions specifically targeting this population segment. The goal of this study was to develop and assess a hands-on activity addressing the lethal effect of sunlight. Using a mixed-method approach based on a case-control pre-/post-test design, the effectiveness of this activity was evaluated following its implementation in four high schools in Portugal. Data collected through questionnaires, classroom observations, analysis of activity reports and interviews with 140 12th-grade science students aged 17.10?±?0.67?years old attending biology classes reveal that the activity had a positive impact on student knowledge about the effects of solar UV radiation and the importance of safe sunlight exposure. The implications of these findings for health and biology education--namely, concerning the instructional design of practical activities in this scope--are discussed.