consideration (Simon, 1989). Experimentation can serve to generate observations
(expected as well as unanticipated or “anomalous” data) in order to induce a hypothesis to
account for the pattern of data produced (discovery context) or to test the tenability of an
existing hypothesis under consideration (confirmation/verification context). The isolation
and control of variables and the systematic combination of variables are particular skills
that have been investigated. The control of variables is a basic, domain-general strategy
that allows valid inferences and is an important strategic acquisition because it constrains
the search of possible experiments (Klahr, 2000). In addition to being essential for investigation,
producing unconfounded experiments yield evidence that is interpretable and therefore
facilitates inferential skills. Confounded experiments yield indeterminate evidence,
thereby making valid inferences and subsequent knowledge gain impossible.