Middle Ages for Kids http://medievaleurope.mrdonn.org/
The Middle Ages for Kids http://www.kathimitchell.com/middleages.htm
Kids Connect Middle Ages http://www.kidskonnect.com/subject-index/16-history/272-middle-ages.html
What was it like in the Middle Ages? http://www.learner.org/interactives/middleages/feudal.html
History for Kids http://www.historyforkids.org/learn/medieval/index.htm
Social Studies for Kids http://www.socialstudiesforkids.com/subjects/middleages.htm
Wikipedia explores antisemitism in the Middle Ages. http://en.wikipedia.org/wiki/Antisemitism_in_Europe_(Middle_Ages)
Some history behind antisemitism. http://remember.org/History.root.classical.html
Here are some other resources that you can't find on the internet: School Library Local Public Library