Illustrative practical work is commonly used in chemistry education to enrich students' understandings of chemical phenomena. However, it is possible that such practical work may not serve to foster understanding but rather cause further confusion. This paper reports the struggles experienced by a group of senior (Year 12) secondary chemistry students as they sought to understand redox chemical concepts involved in the reactions occurring when steel wool is added to copper sulfate solution. The results showed that the students lacked the skills required to make accurate observations during the practical work. Nor were they able to link the observed phenomena with previously taught redox concepts. The paper also presents possible ways to overcome the difficulties encountered by students as they move between macroscopic and submicroscopic levels of representation of redox reactions.