In efforts to understand and promote long-term interest in science, much work has focused on measuring students' interest in topics of science, typically with surveys. This approach has challenges, as interest in a topic may not necessarily indicate interest in scientific practices and pursuits. An underexplored and perhaps productive way to gauge and foster interest in science is to understand the ways in which students express curiosity about the nature of an object, phenomena, or a given topic. This study explores the nature and prevalence of students' expressions of science-relevant curiosity such as wonderment about causal mechanisms, teleological explanations, and inconsistencies in observations. We coded student photojournal entries and interview responses to explore (1) how wonderment can be characterized not by science topic or domain, but rather by the aspects of scientific inquiry practice they reflect, (2) the variation in such science-relevant curiosity expression in a small sample (N = 19) of sixth-grade students, and (3) how individual variation in curiosity expression relates to reported interest in science. We found that a qualitative approach using photojournaling and interviews captured a wide variation in curiosity expression among students, and brief cases analyses (N = 3) demonstrate that students with differing patterns of curiosity expression talk about their interest in science differently.