The Portuguese curriculum for science teaching in middle schools has a constructivist focus, promotes Science-Technology-Society-Environment perspective, and encourages the development of competences in subject knowledge, reasoning, communication skills, scientific and social attitudes (Galvão et al, 2002). Besides, it emphasizes that science should be taught through inquiry. Scientific inquiry involves complex reasoning as well as development of exploration processes that require curiosity, interest and perseverance (Ask & Klein, 2000). Learning is an active process for the pupils and the teacher’s role must change from expositor to facilitator (NRC, 2000). As the teacher plans the lesson and organizes the classroom environment he must now be prepared to facilitate the engagement of pupils in new classroom activities that promote learning with conceptual understanding (Hewson & Hewson, 1989). Many authors (NRC, 1996; Woolnough, 1998; Novak & Krajick, 2006) suggest scientific inquiry use in classroom as a way to increase student’s engagement with their own learning and to create successful learning situations. However, in order to apply these strategies and engage pupils in this kind of tasks it is needed that teachers break those routines associated to traditional teaching and change into one that holds for the development of competences and research (Cachapuz, Praia & Jorge, 2004; Sagor, 2005). This requires a conceptual change on the part of teachers (Borko & Putnam, 1992; Pajares, 1992). Considering the classroom as a space for discursive interaction, it does matter that we know the mechanisms that regulate the speaking periods of the teacher and pupils too. Speech can be studied as a dialogic and polyphonic production (Bakhtin, 2004). Dialogic because it happens in a space for interaction with the other and gets organized by means of that interaction according to the interests of the speaker and of the images he creates of the listener or which he thinks the listener has about him. It is also polyphonic since it is spoken by a specific subject, the enunciator, whose speech is supported by other voices, that is, other speeches made before his own. This study aims to describe teacher’s and pupils’ role, in classroom discursive space, when they have broken with traditional teaching and adopted scientific inquiry. It is part of an extended study that involved schoolteachers implementing inquiry activities according to the new Orientations, that aims answers: how the teacher’s and pupils’ voices reflect the different roles that are due during the implementation of scientific inquiry in classroom?

The research reported in this study is qualitative, adopting an interpretative orientation (Borko et al, 2008). One physics and chemistry teacher and a group of two pupils participated in this study. Both the pupils are 14 years old and males. The school belongs to Lisbon area. The data sources used in this study were the interactions among teacher and pupils during the implementation of scientific inquiry (Patton, 1990). The conversations that took place between pupils and teacher were audio taped. From a discursive perspective the study of language involve the reading of verbatim transcripts to develop a system of categories to codify and categorize the voices expressed by the enunciators. The enunciator is the subject who speaks and invites different voices to compose his speech. This is the principle of "dialogism" of Bakhtin (2004) that we speak with words of others. This study contemplates three enunciators: teacher and two pupils.

Among the voices spotted, we believe that five of them contain enough evidence of teacher’s role changes. The same applies to the pupils as a consequence of the new teaching strategy. The pupils have to assume an active role in their own learning because the teacher only gives them some orientations. That makes the pupils think differently in order to perform the activities himself, once the new role of the teacher in the discursive interaction, only allows him to guide pupils while they improve their knowledge. In this new context, we not only identify the changes through the speaking project for both teacher and pupils, we also recognise a reconfiguration in their interactions as a result of the influence of the teacher’s speech on the pupils’. The study showed that scientific inquiry activities can be developed in classroom promoting changes in the interlocutors’ roles and the reconfiguration of discursive space.