This book is part of a book series called How Things Work .

This book has been graded for interest at 7-10 years.

This book was published 2011 by Child's World .

JENNIFER SWANSON is the author of over 14 nonfiction books for children. She specializes in writing about science and technology. Her children's book Body Bugs: Invisible Creatures Lurking Inside You was a 2012 Book of Note with the Pennsylvania Librarian Association. Jennifer has a M. S. Ed in K-8 science and is a middle school science instructor.