Apologia Young Explorer Series is always discounted at Schoolhouse Publishing!
The Young Explorer series, written by Jeannie Fulbright, is my favorite elementary science program. I can't say enough about these wonderful, colorful books, their creative ideas, and how easy they are to use. They encourage lap booking - which I love.
These beautiful, colorful, and gorgeously illustrated science textbooks are for elementary students grades K - 6. Jeannie Fulbright has written engaging text and included narration prompts for you (Charlotte Mason style). She replaces worksheets and tests with notebook assignments, lots of worthwhile experiments, projects and activities (all extremely do-able). No other resources or teacher manuals are needed, however there are simple experiments throughout each volume. Each of the books are independant and could be used as a full year curriculum. There are also Notebooking Journals available for some of the series, with more being released in the coming months.
Since I used these textbooks before the journals were released, I don't see the journals as being necessary. We created our own lap books (all suggestions and ideas are included in the textbooks). However, I know many homeschool moms who have enjoyed the ease of having the lapbook and notebook components ready at your fingertips. So, all of that to say that these journals provide the motivation for lap booking, should you choose to use them, but the textbooks stand beautifully alone if you'd rather do it yourself.