VICENTE MELLADO, MARI ´ A LUISA BERMEJO, LORENZO J. BLANCO and CONSTANTINO RUIZ THE CLASSROOM PRACTICE OF A PROSPECTIVE SECONDARY BIOLOGY TEACHER AND HIS CONCEPTIONS OF THE NATURE OF SCIENCE AND OF TEACHING AND LEARNING SCIENCE Received: 8 June 2006; Accepted: 25 April 2007 ABSTRACT. We describe research carried out with a prospective secondary biology teacher, whom we shall call Miguel. The teacher_s conceptions of the nature of science and of learning and teaching science were analyzed and compared with his classroom practice when teaching science lessons. The data gathering procedures were interviews analyzed by means of cognitive maps and classroom observations. The results reflected Miguel_s relativist conceptions of the nature of science that were consistent with his constructivist orientation in learning and teaching. In the classroom, however, he followed a strategy of transmission of external knowledge based exclusively on teacher explanations, the students being regarded as mere passive receptors of that knowledge. Miguel_s classroom behavior was completely contrary to his conceptions, which were to reinforce the students_ alternative ideas through debate, and not by means of teacher explanation. KEY WORDS: classroom behaviour, conceptions, secondary prospective science teacher INTRODUCTION From a constructivist perspective, science teachers are considered as having conceptions about the nature of science, about scientific concepts, and about how to learn and teach them (Gil-Pe ´rez, 1993; Hewson & Hewson, 1989). These conceptions are usually deeply rooted, and a teacher_s first step in his or her education and professional development should be to reflect on these conceptions critically and analytically (Hewson, Tabachnick, Zeichner, & Lemberger, 1999). In prospective teachers, the conceptions are the fruit of the many years they themselves spent at school (Gunstone, Slattery, Bair & Northfield, 1993; Gustafson & Rowell, 1995; Young & Kellogg, 1993), and they are more stable the longer they have been a part of each person_s belief system (Pajares, 1992). Most of the novice teachers analyzed by Simmons, Emory, Carter, Coker, Finnegan, Crockett, Richardson et al. (1999) considered that the best form in which their students can learn International Journal of Science and Mathematics Education # National Science Council, Taiwan (2007)