MFW has great lists (all books read & approved by Christian curriculum writers of MFW) of suggested books to read along with each unit. It has been very convenient to check out these books from our local libraries, which we visit weekly. Here are the science units we have studied so far.
(Click on photo to enlarge.)
Science Unit 7- Rivers
Science Unit 6- Thunder & Lightning
Science Unit 5- Rain
Science Unit 4- Trees