This study examines the resolution of a modelling problem about a sedimentary basin, in a cooperative context, through discourse analysis. This work makes part of a research project about the contribution of Geology laboratory problems to the acquisition of students’ scientific competencies, in terms of PISA (OECD, 2006).

To do so, the modelling, mental or material, helps students to reinforce their knowledge about the natural world and to “promote more authentic science education” (Justi, 2011, p. 97)

We understand model as Gilbert, Boulter & Elmer (2000) as a partial representation of natural phenomena. It has a range well know of advantages and disadvantages. Modelling is the main representation tool in science (Giere, 2004), which is a fundamental practice in learning science. However, we have to take into account that they aren’t copies of reality (Justi, 2011), that is to say, we must keep in mind what is not represented.

In this proposal, we consider that the main limitation of the sedimentary basin is the lack of representation of process formation of the basin, there are only the elements. In order to solve this constraint, students should make a verbal model for this dimension, i.e., using analogies in speech (Gilbert, Boulter & Elmer, 2000).

The model co-construction requires involved students explicitly explainning the theoretical models, such as erosion and sedimentary processes, as well as to justify properly the chosen criteria to build the basin. This is a greater contribution to the acquisition of scientific competency in terms of Spanish curriculum:

 “The building of these explanations and predict models is performed through procedures of search, direct observation or experimentation, and formulating hypothesis which will have to be contrasted” MEC (2007, p. 690)

In Geology, as Schumm (1991) points out, the interpretation of past events and prediction of the future events requires the reasoning by analogies. These analogical relations are the basis to build models (Sibley, 2009).

Difficulties in teaching and learning Geology have been addressed by several authors: in understanding the geological time through strata analysis (Peters & Mattietti, 2011); in acknowledging the Earth’s age (Dahl, Anderson & Libarkin, 2005); in recognising the origin of rocks and relief (Pedrinaci, 2001); or in understanding the Earth’s internal structure (Lillo, 1994).

In this modelling context, we addressed some difficulties related to understand and to use knowledge about stratigraphy. Our research’s objective is to explore students’ reasoning during modelling a sedimentary basin. This goal is particularized in two research questions:

1. How do students build the material model using the analogies?

2. How do students justify their steps to build this model?

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