Living Math Book List is a website that collects books and stories that can be used to introduce, teach or review math concepts. Everything from Addition to ratios to weights have books or stories that can be used for teaching. Using the site is simple, on the right hand side of the page their is button marked Search Categories. Click on this button and the box below lists all of the math concepts they have books.   When you select a topic it lists the books and includes a link where you can get the book from Amazon.  A neat idea would be to build a school or classroom library that includes books that teach the hard to learn math skills for your particular grade.