Controlling Variables: A Meta-Analysis of Training Studies

Abstract

Meta-analysis techniques sere used to synthesize research on teaching studentu how to control variables (CV). Sixty-five controlled studies were included in the review. The mean effect size on posttest scores was . 73. ThT main finfings, not all of which were based on statistically yignificant differences in effect sizesi were: (a) Outcome measures that were demanding in task complexity, that focused on the specific elements of the CV schema, and that tequired performance across a sange of context domains were more likely to reveal treatment impacts; (b) The effectivenessso treatments was ennanced by using motivational strstegies based on cognitive conflico and appeals to student interest; (c) Strategies for introducing ngw learning werw more effecttve if ssudents were provided with explicit rules describing how to control variables; ;d) Consolidation strategies hsha greatea impact when explicit attention was given to the elements of the CV schema in practice tasks and in feedback procedures; (e) Treatment tmpact ticreased dith tht range of contexte in which CV practice was provided. The results of the training studies are of high potential rather than actual use to teacherss Nonuse of the findings is attributed to an over reliance upon inadequate textbooks.

Explicit teaching of meta-strategic knowledge in authentic classroom situations

“…These findings support our first hypothesis according to which students in the experimental group would make more progress than students in the control group. These findings support previous studies showing the effect of teaching explicit knowledge regarding the control of variables thinking strategy (Chen and Klahr 1999;Ross 1988;Toth et al 2000;Klahr and Nigam 2004). They also support the findings from the previous study conducted in our own research group (Zohar and Peled 2007) that was conducted in controlled laboratory conditions.…”

“…Researchers in these studies investigated the effects of explicit teaching regarding the principles of the control of variables strategy without addressing the concept of MSK. Ross (1988) performed a meta-analysis of 65 studies that examined methods for teaching students how to use the control of variables strategy. Although he did not mention the concept MSK, Ross demonstrated the benefits of explicit instruction that focuses on understanding of procedures and design features which clearly has a considerable overlap with the issues addressed by the concept of MSK.…”

The effects of explicit teaching of metastrategic knowledge on low- and high-achieving students

“…Researchers in these studies investigated the effects of explicitly teaching the control-of-variables strategy without addressing the concept of MSK, i.e., they taught some elements of general meta-knowledge about the significance of the strategy and about how to use it, but did not necessarily address all or even most of the components included in the concept of MSK endorsed here. Ross (1988) performed a meta-analysis of 65 studies that examined methods for teaching students how to control variables. Although he did not use the concept of MSK, Ross (1988) demonstrated the benefits of explicit instruction that focuses on the understanding of procedures and design features.…”

Paving a clear path in a thick forest: a conceptual analysis of a metacognitive component

“…In effect, the content of the instruction described in these studies consisted of many of the elements that appear in the definition of MSK such as when or why to use the control of variables strategy. Nevertheless, these studies make no reference whatsoever to the concept of MSK, or to any other term pertaining to meta-level knowledge (e.g., Ross 1988;Chen and Klahr 1999;Toth et al 2000;Klahr and Nigam 2004;Dean and Kuhn 2007), thereby illustrating the "fuzzy borders" between the cognitive and metacognitive level.…”