Traditionally, within the biological sciences, laboratory-based practical classes have been conducted on the basis of the students following a 'recipe', in order to achieve a set of predictable results. Widening access to higher education and the subsequent increases in class size have exposed the limitations of this teaching method, and highlighted the fact that many traditional teaching and assessment strategies do not support an active-learning environment. This paper reports a project which was undertaken within the context of the Enterprise in Higher Education initiative, which has student-centred learning at its core. Three new open-ended, problem-based laboratory projects suitable for students working in groups of tour were developed. Students, assigned to a group and to a project, were asked to research a scientific problem, design and conduct appropriate experiments within time and budgetary constraints, and present their work in the form of a scientific poster. The work was assessed by staff, the students themselves (using a self- and peer-assessment procedure) and industrial contacts; the letter also sponsored prizes for the best group effort. This initiative won a Partnership Award for innovative teaching.