Identify the games that best meet the needs and expectations of teachers and objectives of their courses remains a necessity about the integration of serious games among active teaching methods. Indeed, several serious games have developed in recent years, and it is often difficult for a teacher, not a computer scientist in particular, to find a game that meets these specific needs. Our aim is to develop models and tools enabling the teacher to find serious games adapted to his needs, considering user feedback and their traces of interaction with the game. To this end, we have explored the evaluation methods of serious games as well as methods of extracting knowledge from traces and texts. In this paper, we present our method of knowledge extraction of educational objectives. Thus, our proposal is assisting and supporting teachers/trainers to choose serious games and easily integrate them into their learning processes and devices.