Class diagrams may be used as learning resources for the generation of software engineers’ competencies. However, when they are open learning resources, they may lack information about the quality they contain. It may represent a drawback in the generation of the competencies since defects included in them may hinder the learning objective that generates the competencies. This work reviews 109 open class diagrams to identify the most common defects, it also analyzes some related work to identify what are the quality attributes that class diagrams should contain and the metrics used to evaluate them. The review of the class diagrams is performed based on the attributes and values proposed in the related works. As a result, 15 defects and their frequency, a total of 323 defects were identified. In addition, four Class Diagram cases are presented and explained according to the evaluation of the quality attributes.
