This paper focuses on one Grade 5 class (9 females; 9 males) who worked in student-pairs to view five digital learning object (DLO) lessons created by the authors and meant to introduce students to the nature of models, the particle nature of matter, and physical change. Specifically, the paper focuses on whether DLO design elements could assist student-pairs to identify salient features needed to distinguish among particle models of solids, liquids, and gases and explain particle behavior during physical change. The primary data source is the student-pairs' responses to on-line questions embedded in the DLOs at the end of Lesson 3 and at the beginning, middle, and end of Lesson 4. Data shows that nearly every student-pair acknowledged the importance of noticing movement, spacing, and holding when trying to distinguish among particle models of solids, liquids, and gases. Further, they identified changes to movement, spacing, and holding as the salient features of physical change. The paper concludes with recommendations for future research.