Dear Terence and all Just a quick note to thank you and others for picking up this thread, and for the many useful comments that followed. Best Jude National Institute of Education (Singapore) http://www.nie.edu.sg DISCLAIMER : The information contained in this email, including any attachments, may contain confidential information. This email is intended only for the use of the addressee(s) listed above. Unauthorised sight, dissemination or any other use of the information contained in this email is strictly prohibited. If you have received this email by fault, please notify the sender and delete it immediately.