I've been a fan of Scholatic books since I was little and now my girls read them too. As a homeschooling family we use their website as a resource in our teachings. They help me with lesson plans and an entire sections just for kids. I love the worksheets and there are over 1500+ I don't have to have books everywhere. I just print out what I need when we need it.
Right now my 4th grader is using the adding fractions worksheets. There are also math sheets for my 1st grader and up to 8th grade! There are both reading and math sheets and they are award winning making my job so much easier.