Instructors: Access to PowerWeb for Environmental Science is now available FREE with all new text purchases (a $15 value). In addition, you may also package the Environmental Science Essential Study Partner CD-ROM (a $20 value) at NO COST. For more details about PowerWeb for Environmental Science and the Environmental Science Essential Study Partner CD-ROM, see the supplements section of the "Information Center". You must contact your McGraw-Hill sales representative for the correct package ISBN in order to take advantage of this Value Package offering. Or, email heather_wagner@mcgraw-hill.com.