1.1: Introduction Difficulty Level: At Grade Created by: CK-12 Share Add to Library Turn In Read Resources Details Loading... Notes/Highlights Having trouble? Report an issue. Color Highlighted Text Notes Show More Image Attributions Show Hide Details Description No description available here... Date Created: Feb 23, 2012 Last Modified: Aug 14, 2014 Save or share your relevant files like activites, homework and worksheet.To add resources, you must be the owner of the section. Click Customize to make your own copy.