Welcome to the 30 Day Challenge for July, where we’ll be looking at the STEM fields: Science, Technology, Engineering, and Math. I originally conceived of the as the Science & Math Challenge so those two categories will get more attention, but we will touch on all of them.

Today we want to know about your favorite nonfiction physical science or math book. For our purposes physical science includes physics, chemistry, astronomy, geology, and similar subjects; biology and social sciences will be tomorrow.

What are your favorites? Is there one particular subject you tend to read about, or are you all over the map? Has a science book ever changed your mind about something in a major way?

Bonus: Favorite physical science or math book for kids.