The transition from natural to rational numbers is difficult for most elementary school children. A major cause for these difficulties is assumed to be the "conceptual change" they need to undergo in order to see that several natural number properties do not apply to rational numbers. To appropriately handle pupils' difficulties,…

The natural number bias is known to explain many difficulties learners have with understanding rational numbers. The research field distinguishes three aspects where natural number properties are sometimes inappropriately applied in rational number tasks: density, size, and operations. The overall goal of this study was to characterize the…