If anyone is planning on doing a bug unit you might want to look at reading James and the Giant Peach. I think it is at about a 4th grade reading level, but I've been reading it to my 6yo and 4yo and they are loving it. It is the first novel that we have read, eveything else has been picture books. They have taken to it well. It does have some illustrations but not on every page. The chapters are also short, about 2-3 pages, so it is easy to take breaks or stop for the night (though the kids keep begging for more). We plan on seeing the movie after we finish and talk about the differences between the two. Anyways, just wanted to let you all know in case there is someone looking for ideas.
