Third, fifth, and seventh graders selected the best strategy (rounding up or rounding down) for estimating answers to two-digit addition problems. Executive function measures were collected for each individual. Data showed that (a) children's skill at both strategy selection and execution improved with age and (b) increased efficiency in executive…

We explore the immediate and longer term consequences of different types of instruction about a central topic in middle school science: the "Control of Variables Strategy" (CVS). CVS represents the procedural and conceptual basis for designing simple, unconfounded experiments, such that unambiguous causal inferences can be made. CVS appears to be…

The present study explores how suppositions which conflict with accepted beliefs are represented and reasoned about. Two studies test the predictions regarding the nature and developmental changes in children's ability to represent and reason about hypothetical or make-believe suppositions which violate their everyday knowledge and beliefs. In…