Abstract
Research into children's understanding of probability has revealed a number of significant misconceptions. But much research has been eclectic, with piecemeal influence on classroom practice in both teaching and assessment A good test of probabilistic understanding is sorely lacking. This paper uses the results of previous research to propose a multi-dimensional classification of the very wide range of situations and appropriate responses which together make up what we refer to as "an understanding of the idea of probability". Ways in which the classification may be applied to classifying assessment questions and complete tests are discussed briefly.