Explored 5th graders' reasoning about data modeling by conducting 2 design experiments. In Exp 1, 10 Ss assumed the role of data analysts and developed a survey, collected and coded data, and used the dynamic notations of hypermedia to compare the lifestyles of American colonists to their own. In Exp 2, 2 5th graders and their teacher developed and used a randomized distribution to reason about the likelihood of ESP. Analysis of student conversations, including their dialogue with the teacher-researcher, indicated that the construction of data was an important preamble to description and inference. Students' ideas about many elements of data modeling were related to forms of notation. Experimentation afforded a framework for teaching about inference, grounded by the creation of a randomization distribution of the students' data.