Deconstructing the Instruction of the Control of Variables Strategy: Key Components of Science Instruction
Author: Freer, Benjamin D.
Date: 2011-00-00
Type: Reports - Research
Subjects: Direct Instruction,Intervention,Student Reaction,Scientific Methodology,Science Achievement,After School Programs,Science Experiments,Science Instruction,Elementary School Students,Educational Strategies,Individualized Instruction,Class Activities,Grade 3,Grade 4,Instructional Effectiveness,Low Achievement,Predictor Variables,Pretests Posttests,Longitudinal Studies

A crucial element of the logic of the scientific method is the Control of Variables Strategy (CVS), in which conclusions about causal relations are enabled by manipulating a focal variable of interest while holding all other variables constant. Understanding CVS in elementary grades generally is poor, but can be improved with systematic instruction. Chen and Klahr (1999) developed a brief teaching intervention combining direct instruction in CVS with hands-on experience in constructing experiments. The method has been shown to be effective in individual instruction and in classroom settings (Klahr &amp; Nigam, 2004; Lorch et al., 2010). Although relatively brief, the intervention is sufficiently complex that questions remain concerning which of its components are critical to success. Further, the intervention is effective in classrooms that are relatively high-achieving in science, but less effective in lower-achieving classrooms (Lorch et al., 2010). In the authors' program of research, they have &quot;deconstructed&quot; the teaching intervention to determine its most important components and to examine strategies for improving learning for all students. The studies to be discussed in this presentation center on two questions: What components of the Chen and Klahr (1999) teaching intervention are most important in producing and maintaining children's understanding of CVS? How can individuals build from this knowledge to improve understanding of CVS for all students? The studies discussed in the symposium all were conducted in public elementary schools. Some examined classroom-based interventions that were delivered as part of regular instruction in 4th grade classrooms of 20-28 students. Other studies involved individual sessions with 3rd or 4th grade students, either during the school day or as part of an after-school program. The research described here clarifies several important components that influence learning of the Control of Variables Strategy by 4th-grade students. First, combining the components of teacher-led instruction and student-led manipulation benefits learning in a way that neither element alone achieves. Second, opportunities for student-teacher interaction produced more learning than instruction that did not call for student response. Third, attempts to increase learning among children from schools low in science achievement by &quot;simplifying&quot; CVS instruction were not successful. That is, focusing instruction on unconfounded experiments (&quot;positive&quot; examples in Study 3) or reducing the number of variables that students needed to attend to during instruction (Study 4) were not as effective as instruction that began with confounded experiments or required children to attend to more variables, particularly among children from schools lower in average science achievement. Both of the latter conditions may place more stress on the rationale for CVS and on why all variables other than the focal one must be controlled. Fourth, the benefits of CVS instruction are best consolidated and maintained over time when instruction precedes the student-led design of ramps experiments and CVS testing. Finally, the major challenge for future efforts to improve CVS understanding is to improve the effectiveness of instruction for children who may be less prepared for science instruction. For these children, it may be essential to place more emphasis on promoting understanding of the goal of scientific experiments prior to instruction in the manipulation and control of variables. References are appended.