During the grammar stage for us, science is mostly a matter of exploring the world, going to science museums, doing ad hoc experiments, and finding out the answers to questions about the world around us.  Starting toward the end of the grammar stage and through the logic stage, we use the Prentice Hall Explorer books.  For high school, after much research, we decided to use Dr. Jay Wile's books.  Although our family doesn't agree completely with his young Earth creationist theories, we love the structure very sensible structure of his books and use it as an opportunity to talk about the intersection of faith and science.  In case your wondering, I believe that God most certainly created the universe and is our loving Father, but whether it literally took 6 days or millions of years is something I don't really get worked up about.  The latter possibility seems more likely to me, but I'll have to wait until Heaven to know for sure!

Prentice Hall Science Explorer

This series is intended to be for middle school students.  Each book covers a particular topic like astronomy, botany, chemistry, etc.  There are 16 of them altogether, and they are about 1/3rd the size of a typical science book.  The order doesn't matter, so you choose them in order of the interests of your child.  We start these at the end of the grammar stage or the beginning of the logic stage and use them until high school.

Exploring Creation

This series goes from elementary through high school.  I love the structure of the books, which is sensible.  I love the fact that the books are written to the student by a homeschool advocate who is writing for homeschoolers rather than for the classroom.  He presumes no scientific knowledge on the part of the parent.  I don't love the young Earth strict creationism as I mentioned above, but it beats the opposite extreme any day and provides opportunities for discussion.  I'm sending you to Christianbook.com for this one.