Spatial play in early childhood is associated with a variety of spatial and cognitive skills. However, these associations are often derived from studies in which different tasks are used across different age ranges, leaving open the question of how children's natural behaviors during spatial play develop from infancy into the early preschool years. We used an open-ended spatial play task to establish typically developing children's behaviors from 12 to 48 months (N = 66, 36 girls). Specifically, we observed young children's insertions into a commercially available shape sorter that included six geometric solids with corresponding apertures. Approaches to this task changed with age. Younger children primarily inserted solids into the large top opening, a strategy that did not require spatial alignment for success. Between 24 and 30 months, children shifted to inserting solids into their corresponding side openings, a more spatially and motorically difficult strategy that required aligning solids to their appropriate apertures. This pattern suggests that at 24 months, children begin to adopt more sophisticated strategies for this motor problem-solving task. Older children also completed a higher proportion of successful insertions compared to younger participants, and children successfully inserted rotationally symmetrical shapes (e.g., circle) at younger ages than rotationally asymmetrical shapes (e.g., triangle). This study represents an important first step in providing a detailed baseline of children's natural play behaviors over a wide developmental period that can be used to inform how spatial and cognitive systems contribute to spatial play.