Abstracts - Earli

system, which is essential for the successful solving of complex computations as well.Furthermore, the results will be discussed with reference to the ‘spatial cognition hypothesis’.Can we predict arithmetical reasoning and numerical facility in grade 3, 4 and 5 from the(pre)numerical skills two years earlier?Annemie Desoete, Ghent University, BelgiumPieter Stock, Ghent University, BelgiumIn this study in a longitudinal design the predictive validity of TEDI-MATH on arithmeticalreasoning and numerical facility two years later is investigated in 240 elementary school children.The study reveals that we can predict the numerical facility and the arithmetic reasoning for 43 and48% respectively in grade 3, for 49 and 46% respectively in grade 4, and for 22 and 44%respectively in grade 5. Assessing decomposition and estimation skills in grade 1, 2 and 3 canpredict to some extend the development of early arithmetical reasoning but has no added value inthe prediction of numerical facility in grade 3, 4 and 5, whereas the assessment of calculation skillsand verbal and Arabic knowledge of numbers in grade 1, 2 and 3 seems important to predict bothdomains in middle and upper elementary school children. The study emphasizes the value of thetasks included in TEDI-MATH.A developmental model of the understanding of the concept of fractionJacques Gregoire, Universite catholique de Louvain, BelgiumGaelle Meert, Universite catholique de Louvain, BelgiumLearning fractions is difficult for a lot of students. Step by step, they understand and structuredifferent meanings of fraction: (1) fraction as a division operator, (2) faction as a ratio, and (3)fraction as a number. This evolution reflects a progressive improvement of the understanding ofthe concept of fraction, related to an in-depth reorganization of the child’s concept of number. Thegoal of the current study was to assess the validity of this developmental model, and to enlightenthe conceptual understanding of fraction associated to each step. This developmental model shouldbe used as a reference for the diagnostic of mathematical disabilities.C 629 August 2007 08:30 - 10:30Room: 0.65SymposiumNew methods for old problems – A deeper look at the cognitiveprocesses related to problem solvingChair: Reuven Babai, Tel Aviv University, IsraelChair: Wim Van Dooren, Catholic University of Leuven, BelgiumOrganiser: Reuven Babai, Tel Aviv University, IsraelOrganiser: Wim Van Dooren, Catholic University of Leuven, BelgiumDiscussant: Magda Osman, London University College, United KingdomDiscussant: Stephen R. Campbell, Simon Fraser University, CanadaSince several decades, researchers in science and mathematics problem-solving consider thedistinction between intuitive and analytic forms of reasoning as crucial. Pioneering work on– 131 –