The Predictive Value of Children's Understanding of Indeterminacy and Confounding for Later Mastery of the Control-of-Variables Strategy

Prior research has identified age 9–11 as a critical period for the development of the control-of-variables strategy (CVS). We examine the stability of interindividual differences in children's CVS skills with regard to their precursor skills during this critical developmental period. To this end, we relate two precursor skills of CVS at age 9 to four skills constituting fully developed CVS more than 2 years later, controlling for children's more general cognitive development. Note that N = 170 second- to fourth-graders worked on multiple choice-assessments of their understanding of indeterminacy of evidence and of confounding. We find relations between these two precursor skills and children's CVS skills 2 years later at age 11 in planning, identifying, and interpreting controlled experiments, and in recognizing the inconclusiveness of confounded comparisons (understanding). In accordance with the perspective that both indeterminacy and confounding constitute critical, related yet distinct elements of CVS, both precursor skills contribute to the prediction of later CVS. Together, the two precursor skills can explain 39% of students' later CVS mastery. Overall, the understanding of indeterminacy is a stronger predictor of fully developed CVS than that of confounding. The understanding of confounding, however, is a better predictor of the more difficult CVS sub-skills of understanding the inconclusiveness of confounded comparisons, and of planning a correctly controlled experiment. Importantly, both precursor skills maintain interactive predictive strength when controlling for children's general cognitive abilities and reading comprehension, showing that the developmental dynamics of CVS and its precursor skills cannot be fully ascribed to general cognitive development. We discuss implications of these findings for theories about the development of CVS and broader scientific reasoning.

The relation between the control-of-variables strategy and content knowledge in physics in secondary school

The control-of-variables strategy (CVS) is considered a hallmark in the development of scientific reasoning. It holds that informative experiments need to be contrastive and controlled. Prior evidence suggests that CVS is connected to the acquisition of science content knowledge. In a cross-sectional study involving 1,283 high school students (grades 5 - 13), we investigate whether students’ mastery of CVS is related to their science content knowledge in physics. A latent variable model indicates that CVS is substantially associated with students’ science content knowledge, even when controlling for common effects of general reasoning abilities. Substantial differences in students’ CVS skills and their science content knowledge exist between the lower grade levels in secondary school when students receive physics education. A latent profile analysis shows that the most difficult aspect of CVS is understanding the impact of confounding. This sub-skill emerges in late secondary school and it requires that students master more procedural sub-skills of CVS. These findings indicate that CVS and science content knowledge are closely related within secondary school science contexts. In addition, the findings emphasize that students show various distinct patterns of CVS skills. The identified skill patterns can inform researchers and science educators about the CVS skills that students typically show and thus can be utilized in inquiry activities in different school grades, while the CVS skills students are lacking might be trained in focused interventions.

Improved Application of the Control-of-Variables Strategy as a Collateral Benefit of Inquiry-Based Physics Education in Elementary School

In a quasi-experimental classroom study, we longitudinally investigated whether inquiry-based, content-focused physics instruction improves students’ ability to apply the control-of-variables strategy, a domain-general experimentation skill. Twelve third grade elementary school classes (Mdnage = 9 years, N = 189) were randomly assigned to receive either four different physics curriculum units (intervention) or traditional instruction (control). Experiments were frequent elements in the physics units; however, there was no explicit instruction of the control-of-variables strategy or other experimentation skills. As intended, students in the intervention classes strongly increased their conceptual physics knowledge. More importantly, students in the intervention classes also showed stronger gains in their ability to apply the control-of-variables strategy correctly in novel situations compared to students in the control classes. Thus, a high dose of experimentation had the collateral benefit of improving the transfer of the control-of-variables strategy. The study complements lab-based studies with convergent findings obtained in real classrooms.