Criticism is made of the conventional use of the Darwin finches in teaching. An alternative, 'irruption', theory is presented, to explain the occurrence of the finches in the Galapagos Islands. This postulates that all the species we know today arrived in the archipelago as a mass irruptive migration movement from the north-east. The theory is explained by reference to the European crossbills. In a discussion of the educational role of the theory, it is suggested that we need to make more effort to encourage the creative and critical faculties in advanced work in schools and at undergraduate level. The occasional presentation of alternative theories, and the discussion of their evaluation, are recommended as means to achieving these aims.