Children’s ordinality knowledge predicts later mathematical achievement, yet its development is not well understood. This study examined the early development of numerical ordering skills over 1 year in 150 typically developing Finnish children (Mage,T1 = 4.08 years; 51% boys, 49% girls) using a task in which children ordered sets of items from least to most. Growth mixture modeling revealed varying rates of development in numerical ordering skills. Steep development in numerical ordering skills was associated with higher cardinality skills and number sequence production. Video analysis showed that mainly children who performed well in numerical ordering tasks used their knowledge of the number sequence to determine the order of the sets. These results suggest that numerical ordering skills emerge after cardinality and number sequence skills, potentially requiring the integration of both. (PsycInfo Database Record (c) 2026 APA, all rights reserved)

We suggest that numerical ordering skills in early childhood follow diverse developmental pathways and begin to emerge between ages 3 and 5. Our findings indicate that numerical ordering emerges later than cardinality and number sequence skills, possibly depending on the integration of the two. These results offer new insight into the development of early numerical skills and inform early assessment and instruction. (PsycInfo Database Record (c) 2026 APA, all rights reserved)