Earth Day

Have any good ideas for lessons or activities for Earth Day.  One idea is to go paperless for a day.  It's a real eye opener if you keep track of how many times you would normally pull out a sheet of paper, or worksheet.  Find some alternative methods... use the Activotes or Expressions.  Try shaving cream on the desktop for students to write in, (you'll get your desktops cleaned quite well as a bonus).  What other ideas do you have?  Share them here with a comment.