Check out this cool website created by the Exploratorium for science education:
http://www.exploratorium.edu/evidence/
Evidence: How Do We Know What We Know? examines the scientific process, revealing the ways in which ideas and information become knowledge and understanding. This is done by a case study of human origins.
I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I’ll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be. -Isaac Asimov, scientist and writer (1920-1992)