Learning resources are quite important for online learning while resource provision based on algorithms could not address learners' ubiquitous needs well. Moreover, the structure and content of resources are pre-defined which makes the "Structure" and "Content" coupled closely and could not easily adjust when learners' needs changed. To solve this problem, an automatic resource generation mechanism is needed. In this study, we summarize the main components of resource design and proposed a "Structure-Content Loosely Coupled" resource model (Learning Cell Model). The model separates the structure and content into independent yet connected parts by defining "Dynamic Structure" and "Container". Then, the automatic resource generation mechanism and its supporting system were designed based on the model and used in two 5th Grade classes. Results showed the mechanism and system could generate resources according to learners' needs accurately and improve learners' learning outcomes without increasing their cognitive load. Further, the learners had good attitude, technique acceptance, and satisfaction. Overall, the "Structure-Content Loosely Coupled" model and the proposed mechanism could be used creatively for more flexible and adaptive resource provision. They made the resource generation timely and automatic which helped teachers' resource design. The results are enlightening and foster further research in this field.