Although web-based learning has a lot of advantages over other commonly used technologies in the field, it has its own challenges, too. For example, due to lack of scalability at the infrastructure level, the cost of resource management in e-learning systems has increased significantly. Another example is how to achieve efficient resource utilization in these systems. In addition to dealing with these challenges, other costs should be incurred to provide e-learning services, such as maintenance cost of website, and the associated costs with installation and technical support of software packages. In this paper, we discuss that designing e-learning systems based on cloud computing models is an appropriate approach to dealing with the mentioned challenges. To this end, after an introduction to cloud computing models, we design the architecture of an e-learning system based on the models. Then, we implement the proposed architecture using CloudSim as a simulation tool to evaluate the efficiency of the system. The results demonstrate that by taking the proposed approach, while the system achieves an efficient resource utilization, the scalability of e-learning services increases as well.