In a repeated measures design (pretest, posttest, 1-year follow-up) with 161 3rd-grade students, the authors compared 2 curricula on floating and sinking within constructivist learning environments, varying in instructional support. The 2 curricula differed in the sequencing of content and the teacher's cognitively structuring statements. At the posttest, both instructed groups showed significant gains on a test on understanding the concepts of density and buoyancy force as compared to a baseline group without instruction. One year later, the group of high instructional support was superior to the group of low instructional support on the reduction of misconceptions and the adoption of scientific explanations. Thus, instructional support within constructivist learning environments fostered elementary schoolchildren's conceptual change in the domain of physics.

Curriculum materials explicitly designed to foster teacher learning represent a prominent route to professional development (PD) for teachers. However, it is unclear whether PD can be delivered successfully in the form of teacher self-study of curriculum materials, or whether it has to be scaffolded additionally by an expert. This study investigated effects of expert scaffolding in science-related PD for elementary school teachers with regard to proximal teacher outcomes (i.e., teacher beliefs and motivations), instructional quality, and student achievement. Moreover, mediation of PD effects through proximal teacher outcomes and teachers’ instruction was examined. Seventy-three teachers and 1,039 students participated in the study. Expert scaffolding was implemented in a 3-tiered way: A first group (18 teachers) received PD with extensive scaffolding, a second group (18 teachers) was provided with reduced expert scaffolding, and a third group (18 teachers) received no expert scaffolding and was provided with the curriculum materials only (self-study group). A baseline group (19 teachers) did not participate in science-related PD and completed questionnaires on teacher outcomes only. Scaffolded PD was significantly superior to PD through self-study in terms of teacher beliefs and motivation, instructional quality, and student achievement. Contrary to our hypothesis, PD effects on student learning were mediated only to a small extent by teacher beliefs. However, teachers’ instruction emerged as a substantial mediator of PD effects on student achievement. The results highlight the advantages of additional expert scaffolding in PD based on curriculum materials for the preparation of elementary school teachers for teaching science.

In a study with 56 third-graders, we tested whether reasoning with line graphs can be enhanced by representational activities within a curriculum on floating and sinking of objects in water. We hypothesized that representing mass and volume on the opposite arms of a balance beam allows the simultaneous consideration of both dimensions for a representation of density, and therefore will be particularly helpful for drawing inferences from the slopes of line graphs. In an experimental classrooms study, half of the students used the balance beam, while the other half worked with self-constructed representations. Five months after the instructional unit, students who had been familiarized with the quantitative interpretation of proportional information on the balance beam outperformed students who had worked with self-constructed representation in their interpretation of line graphs referring to density, but only marginally when referring to speed.