With the development of e-learning technology, many specifications of instructional design have been proposed to make learning activity sharable and reusable. With the specifications and sufficient learning resources, the researches further focus on how to provide learners more appropriate learning activities to improve their learning performance. In this paper, we aim to propose a model which can explicitly represent the knowledge of the mechanism to adapt both the learning activity navigation and content presentation according to learners' knowledge of concepts. In our proposed model, each learning unit object contains the learning items and the related concepts, which can be used to perform adaptive content selection, and the sequencing control of these learning unit objects can be explicitly represented as a directed graph to improve the understandability. Based on the learning sequencing graph, an Object Oriented Learning Activity system is implemented and used to design and perform the learning activity of Scaffolding Instruction, named "The evaporation, condensation and boil of water". The Evaluation results show that teachers can effectively design an adaptive learning activity based on concept and misconception hierarchy and the designed learning activity can really improve learners' learning efficacy by the OOLA system. (Contains 12 figures and 3 tables.)