Six 7th-grade students engaged with an instructional sequence involving the use of the "TinkerPlots" software to organize data sets in ways intended to help them construe two attributes: the location of quarters of the data within a sub-range of the entire set, and the spread of those portions. We present evidence of students' thinking about these attributes drawn from their responses to questions posed in the instructional sequence. Comparison of findings from a pre-test and a culminating task suggest that the students enriched their ability to imagine and create hypothetical data from a given representative box plot, and that they became oriented to the spread of portions of a data set as indicated by the length of its quarters.