Measuring preschool children's knowledge of the principle of static equilibrium in the context of building blocks: Validation of a test instrument

Background Preschoolers' knowledge of the principle of static equilibrium is an important research focus for understanding children's science content knowledge. Hitherto studies have mainly used behavioural observation with small samples. Thus, extending these studies with a validated test instrument is desirable. Aims The aim was to validate an instrument (the Centre-of-Mass Test), which is concerned with preschoolers' knowledge of the principle of static equilibrium, using item response theory. In Study 1, the construct structure was tested, and in Study 2, its relationship with stabilities of symmetrical blocks, figural reasoning, figural perception, mental rotation, level of interest, self-concept, motivation, and language capacity was investigated. Samples A total of 217 five- and six-year-old children participated in Study 1 and 166 five- and six-year-old children in Study 2. Methods All tests were administered as paper-pencil picture tests in groups and single interviews. Results In Study 1, the Centre-of-Mass Test's conformity with a 1PL-testlet model with an overall knowledge of static equilibrium and with two subtests, estimation of stable and unstable constructions, was confirmed. Using a 95% binomial distribution, children were categorized into three knowledge categories: geometrical-centre, centre-of-mass, and undifferentiated knowledge. In Study 2, knowledge of the principle of static equilibrium showed positive correlations with figural perception and reasoning, language capacity, and estimation of the stabilities of symmetrical objects. Conclusions The Centre-of-Mass Test measures knowledge of the principle of static equilibrium as a unidimensional construct and mirrors preschoolers' estimations found in previous studies. The acquisition of a more sophisticated static equilibrium knowledge is related to spatial knowledge and language capacity.