Experimentation skills are a central component of scientific thinking, and many studies have investigated whether and when primary-school children develop adequate experimentation strategies. However, the answers to these questions vary substantially depending on the type of task that is used: while discovery tasks, which require children to…

Knowledge of mathematical equivalence, the principle that 2 sides of an equation represent the same value, is a foundational concept in algebra, and this knowledge develops throughout elementary and middle school. Using a construct-modeling approach, we developed an assessment of equivalence knowledge. Second through sixth graders (N = 175)…

The research reported in this paper is focused directly on assessing the validity of the "Teaching Knowledge about Reading and Reading Practices" (TKRRP) assessment. Following the recommendations of the Standards for Educational and Psychological Testing (APA/AERA, 1999), the authors see validation as a process of constructing an…