A core aspect of fairness is the ability to divide resources impartially among others. Previous research has shown that fair sharing behavior is a skill typically learned between the ages of four and six. However, little is known about the cognitive building blocks that develop these skills. Researchers at Harvard University, Boston College and the University of California, Irvine, examined children’s fair sharing behavior in relation to number knowledge, working memory, and cognitive control. A new study published in Child Development showed that symbolic counting skills were the single biggest predictor of children’s fair sharing behavior and that prompting children to count also improved this behavior.