This thesis investigates how experienced preschool teachers integrate digital and analog tools in their teaching. The thesis focuses on so-called STEM teaching, where the subject areas of science, technology, engineering, and mathematics make up the content of integration. The thesis results are based on four studies where empirical material was generated from online surveys, interviews, and documentation of STEM teaching where preschool teachers used digital tools. Article I reports an online survey study that aimed to describe how digital tablets are used to support preschool learning both in general, and with a particular focus on technology education. In Article II, which is a follow up of article I, preschool teachers' implementation of programming activities in their pedagogical practice is investigated using an additional online survey. Article III, which is based on semi-structured interviews, presents a study on how experienced preschool teachers integrate digital tools when teaching science. In Article IV, the results from Study III are deepened through recall interviews and analyses of collected documentation of science activities. The overall results of the thesis show that preschool teachers handle the task of digitalizing preschool teaching by combining digital and analog tools to offer innovative and multidimensional teaching, where the curriculum's fundamental values are in focus. For example, children's perspectives, interests, and agency are brought to the fore by combining digital and analog tools to complement different ways of learning. Preschool teachers see analog resources as fundamental and digital tools as supplementary and reinforcing. In preschool science education, digital tools are purposefully used to expand an already multidimensional teaching and to offer different paths for creative explorations. New activities, such as programming, have also been introduced into practice using digital tools and are often described by teachers as a didactic tool for general education. The community of practice within which these committed teachers work is significant for how, and whether, digitalization initiatives are implemented. This is since routines and prevailing epistemological beliefs within the teachers' working community influence what becomes possible to implement. The results of the thesis demonstrate how digitalized teaching can be used to push the boundaries vii of an already established multidimensional pedagogical practice within STEM when teachers have the knowledge, resources, and intentions for meaningful implementation.