If I had a chance to go back, I would have definitely introduced science reading through these books:
Wilbut Beauchamp "Science stories" Book one, Book two, Book three.
My yet another favourite is "Discovering our world" science for the middle grades series by Wilbur Beauchamp. It is a simple, engaging book, written in a very nice manner. It also has very good illustrations. I wish I had discovered those books earlier!