Many thanks to all who have helped to track down the reference I requested. = (Reasoning , Explanation and proofin sch maths...)It can be located at: http://www.qcashop.org.uk/cgi-bin/qcashop/QCA/02/916.html and costs =A330. Lesley Jones 19 Beechhill Rd Eltham London SE9 1HJ Tel/fax: 020 8 850 3393 Consultant: Mathematics Education and Primary Education