This year at our homeschool co-op, I've been teaching Astronomy to 2nd-6th graders. Here's a pic of my students (three are missing). We just completed this book:
"Exploring Creation with Astronomy" by Jeannie Fulbright. The kids and I had the BEST time going through this book. I was a little skeptical when I first purchased this textbook. The lady at the homeschool bookshop said that her kids would read it for fun in their freetime. When she told me that, I thought to myself, "Oh. You have THOSE kid of kids!." But then, I couldn't believe it! Because throughout the semester MY kids were ACTUALLY READING THIS TEXT BOOK FOR FUN IN THEIR FREETIME! And let me tell you, I don't have THOSE kind of kids! So that says a lot for this text book. There are others in the series that I can't wait to try: botany, anatomy, animals, and more.