My son finished third grade in 2010. He is an average reader and is starting to enjoy reading more and more. I have two daughters that have graduated from third grade. This page includes the 3rd grade reading list my son and daughters have read.
Third grade is a transition year as it begins to mark the transformation out of chapter books being read to them to chapter books they can read on their own. While in 3rd grade, we are still reminding nightly to read as an eight year old has not learned the fun side of reading with all the other distractions in their world.
Reading is by far the best way for children to learn, in fact, the better reader you are, normally the better learner you are as you tend to understand the things around you quicker.