Research MethodsAs educational resources and teaching materials in which 9th-grade students are introduced to statistical inferences hardly exist, the formulated research question involves a dual question. Answering the question requires both the design and the evaluation of the learning trajectory. A design-based research method (Bakker, 2018) seems to address this duality. According to Euler (2017), a design-based research begins with the following question: How can an intended, initially vaguely stated, goal be achieved with a yet-to-be-developed design? As the research process progresses, interventions are conducted and evaluated. Design-based research is characterized by a cyclical process in which educational materials for learning environments are designed, implemented, and evaluated, for following cycle(s) of (re)design and testing (McKenney & Reeves, 2012). In this research project, three cycles were completed, starting from a one-class teaching experiment, through an intervention in three classes, to implementing the learning trajectory in thirteen classes at different schools. Furthermore, between cycles 2 and 3, a case study was conducted into learning from and with technology. In particular, this domain-specific case study focused on the intertwined development of learning techniques for using a digital tool and conceptual understanding. Figure 1.2 provides an overview of the cycles and studies in this research project, and the chapters of the thesis.
RQ3.2: How do the designed steps of the learning trajectory foster students' learning processes?Chapter 5 presents the results of a quantitative study on the effects of the learning trajectory on students' proficiency in the domains of statistical literacy, and inferences in particular. Although the designed learning trajectory