For Peer Review Only                              !" # "$ # !" %& ’(" URL: http://mc.manuscriptcentral.com/tsed Email: editor_ijse@hotmail.co.uk International Journal of Science Education peer-00513320, version 1 - 1 Sep 2010 Author manuscript, published in "International Journal of Science Education 28, 09 (2007) 1041-1062" DOI : 10.1080/09500690600702512