Here you have some websites to practise.
http://kidshealth.org/kid/interactive/digestive_it.html
http://www.vtaide.com/png/digestiveF.htm
http://www.sheppardsoftware.com/health/anatomy/digestion/digestion_game_1.htm
http://science.waltermack.com/flashTeacherTools/biology/digestiveSystemBuilder2a.swf
http://nature.ca/discover/exm/blddgstvsystm/index_e.cfm