The influence of the place-value structure of the Arabic number ...

developmental trajectories of basic numerical competencies and their influence on arithmetic
performance in a longitudinal approach. Thereby, these are the first data that clearly indicate
the prominent role of an understanding of basic numerical concepts as a precursor of
arithmetic capabilities in typical numerical development.
A second line of evidence corroborating the importance of basic numerical
competencies for later arithmetic capabilities comes from recent intervention studies. Dowker
(2001) proposed a modular intervention program that incorporated a distinct module covering
“understanding the role of place-value in number operations and arithmetic” (Dowker, 2001,
p. 7) despite other modules on counting principles, written symbolism for numbers and
arithmetical estimation. More recently, Kaufmann and colleagues (2003) picked up on this
and aimed to investigate possible differential influences of basic numerical concepts such as
counting, transcoding and place-value understanding as well as arithmetic fact knowledge,
and procedural knowledge in an intervention programme training dyscalculic children. Post
interventional evaluation of children’s performance on corresponding numerical tasks
revealed that it was the training of basic numerical competencies from which dyscalculic
children particularly benefitted. Based on these findings Kaufmann et al. (2003) argue that
training of basic numerical knowledge should be a key part of dyscalculia intervention.
However, even these intervention results do not automatically qualify the generalisation of
basic numerical competencies serving as developmental precursors for arithmetic
competencies in typically developing children. In this context, the results of the current study
are meaningful. In a longitudinal approach we observed basic numerical competencies and in
particular place-value understanding in first grade to be a reliable predictor of arithmetic
ability in third grade. Thereby, the present study not only provides first evidence that the
interrelation between early basic numerical competencies and later arithmetic capabilities as
observed in dyscalculia intervention may also hold for typical numerical development. More
particularly, the present results indicate that among basic numerical competencies mastery of
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