Children's understanding of length measurement using a ruler in preschool and primary education: A cross-national longitudinal study

Measuring length is a practice of everyday life and a mathematical principle shared across cultures. A cross-national and longitudinal study was designed to analyse the evolution of the strategies used by Spanish and Portuguese preschoolers and 1st graders when measuring length. The instruments were rulers designed to discriminate between the strategies demonstrated by young children in previous research, taking as variables the number of correct measurements and the strategy used to measure, and country as a covariate. Neither country nor age influenced correct measurements while the ruler used affected the strategy developed by the children. No significant differences were found in the strategies used from preschool to 1st grade, except for the ruler with numbered units and marks. Considering the sequence of sophistication of the strategies, our results reinforce the scaffolding role of discrete units for the understanding of length measurement towards the use of the standard rule