​This study investigates a range of non-normative ideas that pre-service teachers (PSTs) employ in reasoning about sampling variability. This issue was studied in the context of a content course on statistics and probability for pre-service middle-grade teachers at a Midwestern American university. Analysis of seven PSTs' videos and screen records of task-based interviews has articulated fundamental facets of sampling variability that have not yet been fully explicated in the literature, especially with middle-grade PSTs. With the content expectation of sampling variability for middle-grade students as suggested by policy reports in the United States of America, this study is particularly fertile ground for designing curricula that can support middle-grade PSTs' development of critical, specialized content knowledge on sampling variability.