Abstract
We report an example of a research approach aimed at gathering quantitative pieces of evidence of solid findings in mathematics education. The main goal of this project is to provide an additional perspective on solid findings in education, to be used by teachers and by researchers in their work. As a case study, we present a situation of “loss of meaning” in algebra, exploring it with data coming from a large-scale assessment interpreted by means of theoretical lenses. We are able to give information about the extent of the phenomenon and to highlight how the phenomenon is relevant also for high-level students. This approach can provide a link between large-scale assessment results, educational research, and teachers’ practices, and suggests further research issues.