The use of digital teaching materials in mathematics education has gained ground since the firstintroductions of various hard- and software. A distinguishing feature for digital teaching materialsis the possibility to offer interactive and dynamic elements. In this study, eye-tracking is used toexplore students’ reading behaviour when working with mathematics items in a digital environment.In particular, the focus is laid on how students read depending on the extent to which the items offerdynamic elements. Analysis of data from the eye-tracking in combination with students’ responses inthe interviews provide a broad picture of different types of challenges that students may face inworking with dynamic elements. The results also reveal that commonly used dynamic elements asfilms or feedback on given answers are valuable because users emphasize them as useful andinformative.