Hooda Math
This page is filled with math games for third graders. Check it out!
http://hoodamath.com/games/third-grade.php
This is a MUST visit website. Practice verbs, nouns, adjectives, adverbs, prepositions, pronouns, capitalization, and punctuation.
http://www.eduplace.com/kids/hme/k_5/quizzes/index.html#five
With all the games, brain teasers, puzzles, skill practice, lessons, and printable flash cards on this site, you'll love it!
This site offers math homework help, games, and flashcards.
http://www.arcademics.com/games/