Current controversies associated with biotechnological progress (genetically modified crops, animal and human cloning, etc...) preoccupy the media and challenge public thinking. They also challenge science teachers who find themselves in territory not usually a part of traditional, safe science. The new Scottish Advanced Higher Biology and Biotechnology courses expect biology teachers and pupils to discuss the social and ethical issues arising from the expanding uses of new biotechnological techniques. This paper will describe the findings of an ongoing, medium-term evaluation of the effects of a university summer school, concerned with such science and its ramifications, upon biology teachers endeavouring to meet these challenges. Building on interviews with teachers in their school locations and, separately, with some of their (S6) pupils, the research seeks to understand how biology teachers handle controversial discussions and how they rationalize a changing pedagogy of science.