A naturalistic small-scale study was carried out, involving a class from a senior high school in Spain over two years. The students were requested on two occasions to write an essay about chemical change. The essays were subjected to text analysis techniques. Four conceptual profiles were identified: the interactive, the meccano, the kitchen, and the incoherent. The development of these profiles is reported and the implications of our research for the process of teaching the concept of chemical change are given.