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

and 40 is 10 times as large as the distance between 0 and 4) is not influenced by language
differences. Finally, Booth and Siegler (2008) also showed that performance in the number
line task is associated with actual mathematics achievement and in particular the ability to
solve unlearned problems. To substantiate these findings we evaluated whether the size of the
individual mean estimation error in first grade predicted the mathematics mark two years later
by the end of grade three for a subsample of 50 of the German-speaking children. And indeed,
in line with the results of Booth and Siegler (2008) we observed that third grade mathematics
mark became better, the smaller the number line estimation error was in first grade (r = .40; n
= 50). Synced with above findings suggesting two separate representations of single- and twodigit
numbers one could as well assume that as an alternative account to the logarithmic-tolinear
shift, place-value understanding serves as a building block for later arithmetic
competencies.
SUMMARY AND CONCLUSIONS
This study set off to gain new insights in the development of the spatial representation
of number magnitude and the role of language properties on this representation system by
evaluating performance of Italian- and German-speaking first grade children in a number-line
estimation task. The latter languages were chosen as they differ in the organization of their
number word systems. While the order of tens and units in German number words is reversed
as compared to the digital notation (i.e., 27 seven and twenty), no such inversion is present
in Italian. Recently, the inversion property of German number words was shown to pose
specific problems to children when acquiring the Arabic notation of multi-digit numbers
(Zuber et al., 2009). The present data are informative in two respects reflecting language
independent as well as language dependent development:
First, it was observed that comparable to previous results for German-speaking
children estimation performance of Italian-speaking children was accounted for best by a two-
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