Can preschoolers understand zero?
Former studies have revealed inconsistent results whether preschoolers can understand zero or not after they learned the symbolic positive integers. In a more extensive work we investigated what could be the source of those contradictions.
We found that preschoolers as young as 3 years old can handle zero: they solve numerical tasks with zero as efficiently as numerical tasks with positive integers. On the other hand, they are not sure whether zero is a number.
We propose that children may initially understand numbers as a property of sets of items. That is why they can handle the cases when there are no items in a set, but they may think that numbers are only the property of items, and when there are no items, one cannot talk about its quantity. (This is the same explanation that we have proposed when accounting for the sign-value number notation benefit effect.)
Based on these results we propose a few simple recommendations how zero can be taught to preschoolers, and what components can be trained later when they start to learn about negative numbers or multi-power arithmetic.
Krajcsi, A., Kojouharova, P., & Lengyel, G. (2021). Development of Preschoolers’ Understanding of Zero. Frontiers in Psychology, 12, 3169. https://doi.org/10.3389/fpsyg.2021.583734 Or read the preprint version.