Next Generation Science Standards (NGSS) call for integrating knowledge and practice in learning experiences in K-12 science education. "PlantingScience" (PS), an ideal curriculum for use as an NGSS model, is a computer-mediated collaborative learning environment intertwining scientific inquiry, classroom instruction, and online…

This study attempted to determine at what grade levels children develop the ability to combine and control variables, the effect of the elementary science program on this development, and the relationship between a child's ability to control variables and his ability to form combinations of variables. (GS)