What makes you think you have the best answer to a question? Scientists use evidence to back up their conclusions. Find out how to construct an argument, which is an answer based on evidence. Learn how to tell the difference between fact and opinion, and practice matching evidence to conclusions. The Science Sleuths series encourages you to think and act like a scientist. Each book explores an important skill in scientific exploration. Questions and activities help you look at the world around you in a curious way-the scientific way! Book jacket.