Rod & Staff has built a reputation on their ability to present all the necessary information inexpensively in an easy-to-use format. Their science program is no different, offering texts for 2nd-10th grade that are readable, effective, and teacher-supported. If you're looking for elaborate experiments or technically in-depth text, these probably aren't for you, but they do offer a good foundation for further study that is God-centered and reasonably thorough.
For each level there is a student text, teacher's manual, and test packet (there is no test packet for 2nd grade). This is a very straightforward course: students read the text, answer some questions, and then do a hands-on activity or simple experiment. None of the experiments require anything you can't find around the house (or maybe a hardware store), and you don't need any books beside the textbooks and teacher's manuals.
All the older editions are illustrated with black and white photographs and drawings; the new edition upper-level texts have both black and white and full-color images. In the elementary grades, the text appears in story form, describing science concepts and facts in the context of a rural community thoughout the year. The older grade books are just old-fashioned textbook content.
There isn't a biology, or chemistry, or physics text—each book covers the broad spectrum of science topics. Sections to be read are short and manageable, and study questions are to-the-point (though they don't require much if any critical thinking, just reiteration of text content). Again, student text is clear and readable, though not what some would call eloquent. Tests follow each chapter, and are of the true/false, multiple choice, and short answer variety.
Teacher manuals are extremely helpful. Student pages are included in full-size or reduced format (depending on the grade level), along with tips for presenting the lessons, extra experiments and information, answers to objective questions, and more. The teacher manuals are the key to this program, and because each element is so affordable procuring them should be no problem.
Like all Rod & Staff courses, this one is Gospel-oriented. Students are taught the wonders of science as the works of God's Hand (obviously, there's a strong creationist bent here), and nature is seen as a tool God gives man for their mutual benefit. If you want solid science that is solidly Christian, there aren't a lot of better options.
These aren't much to look at. Longtime curriculum publishers like A Beka and BJU Press beat Rod & Staff in terms of visual appeal, and BJU Press definitely has more content, but (especially in the younger grades) kids don't usually need that much science. Instead, they need a solid foundation to support further study later on, and Rod & Staff definitely provides that from an unashamedly Christian point of view.
The main downside is that the hands-on element is often pretty weak, and analogies are often made that most kids won't understand. The Rod & Staff writers come from an agricultural community, and city and suburb kids just don't get references to harvest, tractors, etc. However, these are pretty minor concerns, and this is a good place to start before moving on to something more in-depth like Apologia or BJU Science.