Reasoning about data

In this article, we focus primarily on what we have learned more recently from research about how younger students reason about data, concentrating on ideas that begin developing in early elementary school. We therefore do not review the literature related to statistical inference. One reason for not reviewing that literature here is that a reasonable treatment would require us to review as well the development of probabilistic thinking (see Shaughnessy's review, this volume). But more importantly, there are core ideas in reasoning about data that tend to get shoved to the wings as soon as statistical inference takes the stage. The issues we discuss here, though basic, are still critical to statistical reasoning in the upper grades.