Here are some websites that will help develop and master 5th grade skills. Hopefully you will find them to be fun!!!
Math:
http://www.thegreatmartinicompany.com/
http://www.mathplayground.com/
http://www.coolmath4kids.com/
http://www.funbrain.com/
http://www.aplusmath.com/
ELA:
http://www.scottsboro.org/~flewis/SF%20Reading%20Street/Spelling%20City%205th%20Grade.htm
Social Studies:
http://www.socialstudiesforkids.com/