In an investigation of the learning of science content knowledge in a postgraduate preservice education course, it was found that the 'failure of further learning' effect can be overcome, at least in part, in well-designed courses. Nevertheless the persistence of certain misconceptions among some students did indicate the partial salience of the effect in Postgraduate Certificate in Education science courses. Although the students' confidence in their knowledge of various topics, as indicated in self-audits, was positively related to their actual knowledge as displayed in their test answers, the relationship between confidence and knowledge was not strong, particularly for the biology topics.