Considerable research in the field of Intelligent Tutoring Systems (ITS) has focused on helping students increase learning by taking advantage of technological progress. As the use of social media by learners continues to increase, however, ITS should go beyond teaching based on isolated environments (platforms) and turn toward community-based learning within social networks. In this paper we introduce a new approach to learning based on social networks. This approach takes advantage of the increasing enthusiasm among learners for spending time in social networks. The goal is to use some of that time for learning, by replacing one of the various social game applications with an Intelligent Tutoring Systems (ITS). During a learning session, learners are encouraged to improve their scores by challenging either a score predefined by the system or the scores posted by their Facebook friends. In this paper, we describe a new system called LBC (Learning By Challenging) that enables the user to learn and to share their knowledge and resources in a social environment. It also provides an environment that protects the learner's privacy if he or she so desires.