Open source learning management systems have been widely used in the learning process. However, they do not include options for learning content and process adaptation and personalization. The aim of the paper is to propose an architecture of a learner model based personalized adaptive system. The development of the system proposed in the paper is based on learning management system Moodle. The system is described with the help of such models as a learner model, a content model and an adaptation model. The learner model described the learner in the context of lifelong learning. The content model is based on the vast variety of resources and activities. The adaptation of the system is based on the learner characterizing features and the variety of course topic acquisition sequences. The results of the developed system approbation show that the system is especially suitable for" sensitive" learner category. This category includes learners with the following features: first study year female students with general secondary education, average level of information technology competence, with learning management systems usage experience and Moodle usage experience less than a year.