We propose an inquiry-based science activity centred on the effects of climate change on ocean ecosystems. This activity can be used to improve acquisition of knowledge on the effects of climate change and to promote inquiry skills, such as researching, reading and selecting relevant information, identifying a problem, focusing on a research question, making predictions, planning experiments, observing and registering data, drawing conclusions, developing explanations and communicating findings to class. The activity is suitable for 8- to 13-year-old students and can be used in the classroom.