One approach to examining experimentation skills involves minimizing the role of prior
knowledge to focus specifically on the strategies that can be used regardless of the content
to which they are applied. For example, building on the research tradition of Piaget (e.g.,
Inhelder & Piaget, 1958), Siegler and Liebert (1975) examined the acquisition of experimental
design skills by fifth- and eighth-grade children on a task for which domain-specific
knowledge could not be used. The problem involved determining how to make an electric
train run by finding a particular configuration of four on/off switches. The train was actually
controlled by a secret switch so that the discovery of the correct solution could be
postponed until all 16 combinations were generated.