Resumen

Students have difficulty to use different representational systems. We use the Theory of Conceptual Fields in order to describe and analyze students’ responses to situations in various representational system: numerical, first order algebraic, graphic and verbal written. We conducted the study with 59 students (aged between 15-16 years old) of secondary school. From the analysis we show that students do not "translate" the results of a representational system to another. They can solve exponentially in a representational system (RS) but in a different exponential RS they solve it in a non-exponential way. This indicates that students construct operational invariants for each representational system. That is to say, they build and use different schemes for each one of them.