We have had another great science book. The kids and I just finished reading Ants (Early Bird Nature Books) and they loved it. It starts with a list of words to look out for and later defines them in the glossary. We used the list as a built in list of review questions. It does have some difficult and unfamiliar words (such as thorax and larva) so while most words are simple enough for a first grader, I would have them read it close so you can help with those words. We just read is aloud with the 6, 4, and 2 year old. It has great pictures and diagrams. We will be requesting the rest of the books in this series from the library.