If I'm honest, I have faffed about with Science since starting homeschooling in 2008. I have dipped into different things and been generally unsatisfied with all of it in one way or another. On the surface, I was happy with what I will term 'immersion Science' i.e. grabbing opportunities to teach Science through everyday life, particularly nature walks - heavily inspired by this website - and generally 'seizing the day' whenever I got the chance!
However, this wasn't going to be a system that could last forever and I was still on the lookout for something that was really child friendly, had academic depth, wasn't prescriptive and didn't cost a bomb! The Lord must have spotted me scrabbling around bookshops, surfing the net and poking through homeschool friends' bookshelves, because a very helpful friend eventually recommended a book which pretty much ticks all the boxes for me!
Building Foundations of Scientific Understanding, A Science Curriculum for K-2 is a big fat paperback of 381 pages. I picked it up for around £12 or £13 on Amazon about a year ago. It is written by Bernard J Nebel, Ph.D whose passion for teaching Science in a sensible order is very clear. You can look inside the book on the Amazon site and you will see that he offers ongoing support for free through a yahoo group. He has written two further volumes, for grades 3-5 and 6-8. I'm not brilliant at translating American grades into UK year groups, but it may help you to know that my fairly bright 6 year old can just about work along with her 8 year old sister on the K-2 volume, and the 8 year old can take it all in and it seems to be just about right for her. I have a friend with a daughter in Y6 who will use the second volume when she goes into Y7.
This book is not a word-for-word curriculum and if you don't have the time or just don't want to be totally involved with your child's learning i.e. pre-reading and making sure you understand each chapter, preparing resources and creating worksheets or booklets and then delivering the lesson, then this isn't the book for you. It takes me almost as long to prepare as it does to deliver the lesson, which is a sacrifice I am willing and able to make. It's not the same for everyone though.
When I was considering this book I looked at what other Christians had to say about it - Science is a very controversial subject within the Christian homeschooling community! Someone mentioned that at some point in one of the volumes the chapter on what I will assume to be Creation (I haven't found the chapter yet so can't be sure what it's called!) takes an Old Earth view as opposed to a New Earth view, but the person writing said it would be quite easy to skip that chapter or devise your own instead if you believe in a New Earth. Hope that makes sense and is helpful!