This study investigates the effects of web-based scaffolding in comparison with teacher scaffolding (TS) and no scaffolding (NS) on students' metacognitive skill development in web-search process. The study utilized a static-group pretest--posttest quasi-experimental design. The first experimental group received web-based Internet search scaffolding (WISS) tool treatment; the second experimental group received TS; and the control group had NS. Receiving WISS during an Internet search had a significant effect on the improvement of metacognitive skills when compared with NS; however, it was not significant when compared with TS. While WISS group's scores in all subscales improved significantly compared with those of NS, TS's strategy generation scores were significantly higher than those of NS group. Moreover, WISS group's "control of attention" scores were significantly higher than those of TS group.