Negative+numbers

>
 * http://www.primaryresources.co.uk/online/negnumorder.swf
 * http://www.bbc.co.uk/skillswise/numbers/wholenumbers/whatarenumbers/negativenumbers/
 * http://www.athena.bham.org.uk/old/TR%20Numeracy.htm
 * http://www.wmnet.org.uk/wmnet/custom/files_uploaded/uploaded_resources/851/Higher&Lower-Reveal&Orderv4.swf
 * http://www.bbc.co.uk/education/mathsfile/shockwave/games/laddergame.html