My daughters and I have used this science text. This is a really great elementary and early middle school science curriculum. The text reads like a book and grabs your attention. I must mention that it is written from a creation science perspective, so if that offends you, you might want to stay away from this set. If creation science interests you then this is for you. The book is divided into 16 lessons. At the back of each lesson are experiments and projects that you can complete or skip. To add to this curriculum you can have your kids use a notebook to record any science observations that they make. This really covers flying creatures in detail. I like this science book. My girls sometimes lose focus as we read, but he information is written right at their level. Also, we like that the science experiments are listed, but not "needed".
If you are looking for an elementary or early middle science curriculum, please take a look at this book. We have enjoyed using this in our home.