A Squeak-based educational software - Happy Learning

This paper introduces a Squeak-based educational software - Happy Learning. The software provides powerful tools for carrying out virtual experiments, doing exercises as well as tests, and making courseware. It has rich resources which consist of all kinds of learning materials, such as a large amount of courseware prepared in advance, and exercises from various subjects. In order to organize the resources efficiently, we introduce object deputy model. The model provides view mechanisms, rich semantics, multiple inheritances, and multiple classifications, which can enhance the performance and functions of the system.