Decimals and the related areas of ratio and proportion are recognised as one of the most challenging and complex areas of mathematics for young children to learn. In this study, four dynamic digital representations were used by Year 4 (9-10 years old) students in a set of video-recorded, individual task-based interviews to explore key concepts of decimals. Microgenetic analysis methods were used to detect conceptual changes through specific shifts in the learner's attention. The data collected revealed what features of each dynamic digital representation prompted attention shifts and how these translated to changes in conceptual understanding of decimal fractions.