An online textbook represents a qualitative method of adult education, its preparation requires in-depth work of the author. In this paper we will show the application of modern teaching materials in adult education. We will present concepts related to the main topic, the type of adult education methods and types of online resources. Furthermore, we will present thirteen recommendations for the implementation of online learning based on the characteristics of adult learners. We will describe the online textbook as a qualitative method of adult education. Elements and the starting point for assessing the quality of online textbooks are an important factor in quality assurance. We will demonstrate the benefits of using online textbooks from other types of adult education methods. We will show the four steps in the textbooks preparation and analyse the platforms of higher vocational college textbooks in the project Impletum to be taken into consideration by the writers.
Keywords: online textbook, quality, modern teaching materials, methods of adult education, preparation and writing of online textbooks, characteristics of adult learners, vocational college.