great website for picking "just the right books!"
www.scholastic.com
www.readingrockets.org
Phonics
http://www.starfall.com
http://www.seussville.com
http://www.vocabulary.co.il/phonics/
http://www.spellingcity.com

Math
http://everydaymath.com
www.mathplayground.com

Science
http://kids.nationalgeographic.com/kids

Fun Websites
www.pbskids.org
http://www.funbrain.com
http://www.primarygames.com