This book is part of a book series called Frequently Asked Questions .

This book has been graded for interest at 9-12 years.

There are 40 pages in this book. This book was published 2002 by Kids Can Press .

Valerie Wyatt is an award-winning author more than 14 nonfiction books, many of them about science. She also writes on historical topics and, from time to time, picture books.