Proven to be a useful leaning strategy, concept mapping remains as a challenging skill for students to learn. A key instructional issue is to reduce the difficulty of learning of the strategy. In this study, we incorporated principles of the scaffolding theory in the process of teaching concept mapping strategy with manipulated support of learning the strategy of concept mapping to seek evidence for effectiveness of the manipulation. A 4 x 2 quasi-experimental design of the study with the independent variables of manipulation of the scaffolding support (concept-map drawing, concept-map reading, scaffold-fading, and control groups) and prior knowledge (high versus low background knowledge) was adopted. Participants were 138 5th grade students recruited from 4 different classes. A pre-test on biological science knowledge was administered followed by a 12-week instruction. A post-test and a questionnaire were given to assess the effectiveness of the scaffolding on student learning and their attitude toward the instruction. The results indicated that (a) all experimental groups score higher than control group on text-based representation of knowledge (?) and no differences among experimental groups; (b)For situation model representation, scaffold-fading group score the highest, followed by the concept-map drawing and the concept-map reading and the control groups, with no significant difference between the last two groups; (c) Students with high prior knowledge scored more highly than those with low prior knowledge on both text-based and situation model representation; (d) There was no interaction between teaching strategy and background knowledge; and (e) Scaffold-fading group enjoyed more learning concept mapping and indicated they were more likely to use this strategy in the future. Analysis of their drawing protocol revealed that providing proper scaffolding did make it easy for students to learn relationships between conceptual nodes. The study showed scaffolding as a critical component for successful concept mapping instruction.