Enquiry learning and teaching about the nature of science (NoS) is a key element of science education. We have designed an experimental setting for students aged 12-14 years to exercise enquiry-learning skills and to introduce students to the NoS aspects of creativity and imagination. It also illustrates the impact of carbon dioxide on the growth of algae. Students stated hypotheses, planned experiments and analysed the data, becoming familiar with the NoS aspects mentioned above. The sessions consisted of: an initial 2 hour session to propose hypotheses and predictions and to design the experiment; a 3 hour session to establish the experimental set-up; and a 2 hour session for analysis and interpretation. A well-planned and disciplined class timetable is essential.