Negative Numbers Cauldron (with Severus Snape)
Using the Harry Potter and Craig Barton's excellent ice cubes & fire cubes ideas ( http://www.tes.co.uk/article.aspx?storycode=6145836 ) this powerpoint talks through some examples of calculating with simple addition and subtraction of negative numbers and includes some questions for the children to try. The final page offers a suggested page from the MEP materials (www.intermep.org)