This paper focuses on developing students' informal inference skills, reporting on how a group of third grade students formulated and evaluated data-based inferences using the dynamic statistics data-visualization environment TinkerPlots[TM] (Konold & Miller, 2005), software specifically designed to meet the learning needs of students in the early grades. Children analyzed collected data using TinkerPlots as an investigation tool, and made a presentation of their findings to the whole school. Findings from the study support the view that statistics instruction can promote the development of learners' inferential reasoning at an early age, through an informal, data-based approach. They also suggest that the use of dynamic statistics software has the potential to enhance statistics instruction by making inferential reasoning accessible to young learners. (Contains 9 figures.)