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.