It is evident that "experientially-based" instruction and "active student engagement" are advantageous for effective science learning. However, "hands-on" and "minds-on" aspects can occur in both inquiry and direct science instruction, and convincing comparative evidence for the superiority of either mode remains rare. Thus, the pertinent question the authors seek to address is not whether active, experiential learning of science is more effective than passive, nonexperiential learning. Their research question is whether an inquiry approach or a direct approach to experientially-based instruction is more effective for science concept development, when both approaches are expertly designed and well executed. This research undertook a controlled experimental study comparing the efficacy of carefully designed inquiry instruction and carefully designed direct instruction in realistic science classroom situations at the middle school grades. (Contains 3 figures.)