The purpose of this study was to investigate the relative effectiveness of experimenting with physical manipulatives alone, virtual manipulatives alone, and virtual preceding physical manipulatives (combination environment) on third-grade students' science achievement and conceptual understanding in the domain of state changes of water, focusing on the concepts of evaporation and condensation. A pretest-posttest design was used that involved 208 third-grade students assigned to the three learning conditions. A science achievement test and a two-tier conceptual test were administered to students before and after a teaching intervention. The results revealed that using virtual preceding physical manipulatives and virtual manipulatives alone enhanced students' knowledge gains about evaporation and condensation greater than the use of physical laboratory activities alone. It was also found that the combination environment promoted students' knowledge gains about these concepts equally well as the use of virtual laboratory activities alone. On the other hand, the results showed that using virtual preceding physical manipulatives promoted students' conceptual understanding most efficiently compared to the use of either physical or virtual manipulatives alone; in contrast, experimenting with physical manipulatives alone was least influential for students' conceptual understanding compared to the other manipulatives.