In order to facilitate senior primary school students in Hong Kong to engage in learning by observation of the phenomena related to electrical circuits, a design of a specific courseware system, of which the interactive human-machine interface was created with the use of an open-source software called the LabVNC, for conducting online remote-controlled experiments was developed in this study. The statistically significant results of a pre-test-post-test evaluation study showed that the LabVNC-based system has potential to promote students to learn the target topic under the approach of learning by observation. The assertion of the teacher on the pedagogical value of the remote-controlled experimentation and the enthusiasm of students in using the LabVNC-based system reveal the potential to integrate the use of the LabVNC-based system with the practice of scientific experiments. Based on the feedback from the teacher and students, the existing LabVNC-based system will be refined under the design-based research approach. (Contains 5 figures and 7 tables.)