"Learning by doing" involves completing a practice activity through the method of inquiry. This study combined the predict-observe-explain (POE) inquiry method and hands-on doing processes to develop a cycle-mode POED (predict-observe-explain-do) model with an e-learning system to help students complete a practice activity using scientific inquiry. The study selected 60 sixth-grade students, who were divided into the experimental group (cycle-mode POED model) and the control group (lectures and PowerPoint slides). The students learned how to use hands-on tools to make a "Voltaic Battery Car" and complete the "Car Climbing the Ramp" task with the interdisciplinary knowledge that they had gained. The experiment was conducted over a period of 18 classes for a total duration of 720 min. The results showed that both groups of students improved their learning motivation, learning performance, and hands-on ability. Moreover, the student with lower prior knowledge were able to learn how to complete the activity using the cycle-mode POED model and scientific inquiry. This study developed the cycle-mode POED model to assist students in connecting their scientific conceptual knowledge with practical hands-on doing processes. The research contribution is a pedagogy manuscript for instructors who want to teach scientific inquiry to complete a practice activity.