In physics and chemistry, the development of problem-solving skills is necessary to become an expert. A simple cognitive model to analyse such development is proposed and tested. An exploratory research was conducted with expert professors and students in initial and advanced years. A think aloud procedure was used to obtain relevant data while the participants tried to solve undefined, open problems. Solving these problems required a particular skill representative of expertise: modelling reality using science. More than 1350 solving actions were collected and related to the mental representations elaborated, developed and inter-related by solvers. The proposed model was able to account for expert-novice differences in terms of the respective distributions of solving actions among the mental representations. Large differences appeared in the mental representation of Conceptual scientific Model. In addition, advanced and initial students showed similar and significant averages of unproductive actions, while experts took very few. Experts showed high convergence in their distributions of actions among the mental representations. If the outcomes were replicated with higher external validity, the model could help researchers to analyse the cognitive mechanisms in problem-solving, and teachers to better focus their efforts on specific students’ lacks. Keywords: cognitive model, expert-novice differences, mental representations, problem-solving skills, solving actions

One important skill to be developed in future physicists is modelling reality using physics. Problem-solving is the activity most used to teach, learn and assess physics skills at the university level. However, most of the problems habitually used in physics subjects seem not to encourage developing this skill. Two empirical exploratory studies were conducted. Educational materials were analysed to contrast the hypothesis asserting that most of the academic problems would not help students to develop the modelling skills. Secondly, with the proposed ‘Physics Problem Understanding Model’, two kinds of experimental problems were elaborated. A small group of experts solved the experimental problems in an interview. The hypothesis stated that there would be evident differences between skills associated with the solving procedures of each type of experimental problem. Results served to contrast the cognitive model proposed for sufficiency and supported the hypotheses even though further studies are needed to obtain external validity. Key words: cognitive model, modelling skills, problem solving, problem statements, university level.

El trabajo presenta una revisión de los aspectos metodológicos involucrados en el estudio de las representaciones mentales puestas en juego por las personas para realizar ciertas tareas cognitivas. La revisión se acota al ámbito de la investigación en enseñanza de las ciencias y en particular, a un conjunto de investigaciones que abordan tareas estrechamente relacionadas con la resolución de problemas en Física. La revisión permite analizar y discutir los alcances y limitaciones de las decisiones metodológicas usuales para el estudio de la resolución de problemas en Física. Se ponen en consideración algunas directrices metodológicas plausibles de ser tenidas en cuenta para esta tarea.

The present study explores: a) the relationship between certain characteristics of physics (problem statements and the internal representation that students form after reading the statement; b) the correlation between this representation and the equation generation stage. Seventeen-year-old students of secondary school from Madrid were taken as an accidental sample (N = 189). Certain characteristics of these statements were observed to be favourable instances to solve the problem. Possible implications for the instruction were analysed.

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