The recently published study "The Words Children Hear: Picture Books and the Statistics for Language Learning" investigated how picture books with words added to the number and diversity of words children learn early in life. (More in the abstract; article behind pay wall.)
Naturally, science books for kids are identified in the segment. Recommendations include You Are Stardust by Elin Kelsey and Soyeon Kim (2012); I, Leonardo by Ralph Steadman (1983); and Me…Jane by Patrick McDonnell (2011). Have suggestions? Leave them in a comment on the Science Friday segment page.