Physical models have a long history in chemical research and education. While working with Tanzanian undergraduates studying to becoming chemistry teachers, the authors considered the role of models in promoting learning. At a time of rapid change and development of education in Tanzania, is it helpful to students' learning and understanding to introduce threedimensional representations of sub-microscopic structures using inexpensive alternative models? The expectation was that this question would be answered in the affirmative but the outcome was surprising and illustrates the danger of simply transferring teaching techniques from one cultural context to another.