This study investigated acquisition and transfer of the modeling ability of fifth graders in various domains. Teaching interventions concentrated on the topic of marine ecosystems either through a modeling-based approach or a worksheet-based approach. A quasi-experimental (pre-post comparison study) design was used. The control group (n = 17) received a traditional worksheet-based instruction about ecosystems, whereas the experimental group (n = 16) received an instruction which was based on Stagecast Creator, an object-oriented programming tool, and a set of modeling-based curriculum materials. Paper-and-pencil tests were used both before and after the study to evaluate students' development of specific modeling skills. The data analysis followed both qualitative and quantitative methods. The findings of the present study indicate that (i) the development of modeling ability was effectively enhanced through the modeling-based approach, since, after instruction, students were able to transfer those aspects to unfamiliar contexts; in contrast, the more traditional worksheet-based approach did not promote the development of the same aspects of the modeling skill; and (ii) Stagecast Creator enabled students to construct, test, revise and validate dynamic computer-based models of a marine ecosystem through building, testing and debugging complex rules, routines and programs for simulating multiple behaviours and processes of marine species.