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A literate person must have a basic understanding of how science works. One important component of scientific literacy is understanding that the ability to identify causal relations between variables is central to explaining scientific phenomena and, in turn, that isolating causal relations depends on being able to control irrelevant variables. Indeed, an understanding of the logic of controlling variables is a landmark goal of early science education (National Research Council, 1996; Zimmerman, 2005). Instruction in strategies to control variables (CVS) has been the focus of a great deal of education research (Ross, 1988; Schwichow, Croker, Zimmerman, Hoffler, & Hartig, 2016) and the subject of a long debate in the literature. There continues to be much discussion of the relative merits of embedding instruction of CVS in an authentic, complex scientific context (Allchin, 2014; Kuhn, Ramsey, & Arvidsson, 2015) as opposed to teaching CVS in a simpler and relatively isolated scientific context (Klahr & Chen, 2011; Lorch et al., 2014). This discussion should and will continue; however, there is now substantial empirical evidence that a rudimentary understanding of CVS can be effectively taught to many 4 th-grade students using a relatively brief intervention that emphasizes direct instruction of the key concepts. A protocol first developed by Chen and Klahr (1999) has proven effective at teaching CVS in lab studies. The basic teaching intervention uses a simplified, concrete domain to illustrate the logic of experimentation. For example, a commonly used domain investigates the effects of different variables on how far a ball rolls