Geospatial technologies offer access to geospatial information via digital representations, such as digital maps, and tools for interaction with those representations. The question is whether geography lessons with geospatial technologies really contribute to the development of students' geospatial thinking, in particular geospatial relational thinking, as is suggested in the literature about geospatial technologies in secondary education. This paper reports about the outcomes of a quasi-experimental research project, in which a geography lesson series with geospatial technologies was compared with a conventional geography lesson series that had the same content. Although the lesson series covered only three lessons, the data showed that the lesson series with geospatial technologies contributed significantly more to the development of students' geospatial relational thinking than the conventional lesson series. The effect size was 'medium large'. © 2014 Elsevier Ltd. All rights reserved.