Thinking about the layers of our Earth. @APSscience @CampbellAPS By @CampbellAPS | November 30, 2017 Thinking about the layers of our Earth. @APSscience @CampbellAPS https://t.co/znWpmxR973 Posted in Daily News and tagged @CampbellOutside ← These hardworking kids stayed after school today to continue working on their Jamestown expedition projects! Come s… Thinking about the layers of our Earth. @APSscience @CampbellAPS →