While the potentials of digital textbooks for the learning of mathematics are constantly emphasized, little is known about how the use of digital textbooks actually affects students’ learning processes. In this chapter, the role of digital textbooks in students’ collective construction of mathematical meaning is analyzed in two episodes—one from a third-grade mathematics classroom and one from fifth grade. Based on the framework of semiotic mediation and the instrumental approach, we differentiate between students’ interactions with signs on the artefact level and on the content-level. The results show interactive answering formats and automated feedback as two characteristic features of digital textbooks that present challenges to the students and have the potential to trigger students’ content-related discussions. However, the learning outcome of these discussions is questionable. Therefore, we argue that the tasks and related feedback in digital textbooks need to be carefully designed and thoughtfully implemented in classroom situations.