Unit 7, Making Inferences in Light of Uncertainty, employs modeling and sampling distributions based on these models, to make evidence-based inferences about claims regarding different samples of data. For example, in light of a model of the measurement process of a person’s arm-span, how likely is a particular sample mean arm-span to represent the process of measuring that particular person? The unit also instigates a shift to a context of natural variability. Students participate in an eye illusion experiment and use statistics and models to justify claims about whether or not the illusion affected their perception. The Informal Inference (InI) construct describes milestones in students’ reasoning about statistical inference.