This book, intended for mathematics education professionals and teachers of mathematics, is outstanding in that its contributions come from a broad range of countries and cultures; they are representative of different theoretical perspectives and classroom experiences. All contributors are concerned with helping teachers explore ways to develop children's mathematical understanding appropriate for the new millennium. The authors present complex ideas about mathematical understanding and provide readers with powerful classroom examples. Recommendations for changing the curriculum for young children are also suggested. The book comprehensively documents four years of development in the field. Among the emergent developments described is the importance of context to mathematical development - it is not only the physical context, but also the social context of the classroom and school that stimulate conceptual growth. The book also locates current theoretical perspectives in a broad framework. Finally the book is organized around four interconnected themes all related directly to teaching and learning mathematics.

In Greek geometry, there is an arithmetic of magnitudes in which, in terms of numbers, only integers are involved. This theory of measure is limited to exact measure. Operations on magnitudes cannot be actually numerically calculated, except if those magnitudes are exactly measured by a certain unit. The theory of proportions does not have access to such operations. It cannot be seen as an "arithmetic" of ratios. Even if Euclidean geometry is done in a highly theoretical context, its axioms are essentially semantic. This is contrary to Mahoney's second characteristic. This cannot be said of the theory of proportions, which is less semantic. Only synthetic proofs are considered rigorous in Greek geometry. Arithmetic reasoning is also synthetic, going from the known to the unknown. Finally, analysis is an approach to geometrical problems that has some algebraic characteristics and involves a method for solving problems that is different from the arithmetical approach. 3. GEOMETRIC PROOFS OF ALGEBRAIC RULES Until the second half of the 19th century, Euclid's Elements was considered a model of a mathematical theory. This may be one reason why geometry was used by algebraists as a tool to demonstrate the accuracy of rules otherwise given as numerical algorithms. It may also be that geometry was one way to represent general reasoning without involving specific magnitudes. To go a bit deeper into this, here are three geometric proofs of algebraic rules, the frrst by Al-Khwarizmi, the other two by Cardano.

Social constructivism is just one view of learning that places emphasis on the social aspects of learning. Other theoretical positions, such as activity theory, also emphasise the importance of social interactions. Along with social constructivism, Vygotsky's writings on children's learning have recently also undergone close scru tiny and researchers are attempting a synthesis of aspects ofVygotskian theory and social constructivism. This re-examination of Vygotsky's work is taking place in many other subject fields besides mathematics, such as language learning by young children. It is interesting to speculate why Vygotsky's writings have appealed to so many researchers in different cultures and decades later than his own times. Given the recent increased emphasis on the social nature of learning and on the interactions between student, teacher and context factors, a finer grained analysis of the nature of different theories of learning now seems to be critical, and it was considered that different views of students' learning of mathematics needed to be acknowledged in the discussions of the Working Group."