Once your child starts reading independently, you might be unsure where to start with choosing books - especially where chapter books are concerned. Well I was at Barnes & Noble the other day (oh, how I love that place . . . ) and they make it pretty easy to differentiate between the kinds of chapter books.
The first category is "chapter books" for ages 5 - 8 or grades PreK - 3, which I would call "first chapter books." These books typically have bigger text and often have pictures throughout the chapters. The chapters are shorter, and the syntax is easy to read. Books in this section often come in series, and this section is much smaller than the harder chapter books.
The other kid's chapter book category at B&N is "Young Readers," for ages 7 - 12 and grades 3 - 6. (After that, I guess they can look in the "teen" section?) There are SO many more options now for this reading level than when I was young - lots of seriously great series.
Amazon divides their children's books into the following age categories:
Baby - 2
Ages 3 - 5
Ages 6 - 8
Ages 9 - 12
Scholastic has the same age categories on their website. I guess Barnes & Noble kind of splits the difference. :) The best thing to do is go to an actual bookstore (hopefully you have one nearby!) or library, and spend some time exploring!