The Library of Congress has a fascinating first draft digital image - view the amendments made by John Adams and Benjamin Franklin and others
It also has an online exhibition drafting the constitution which has an essay and further images discussing the writing process . There is a related teacher's lesson plan resource.
Teaching history has some lesson plans and resources for the classroom
For a different response see Frederick Douglass 1852 speech on the meaning of the declaration for African-American slaves
For information on the history and nature of the July 4th celebrations see the White House Historical Association. this has some facinating facts and trivia. Find out about the first celebration in 1801 where Jefferson offered his guests a variety of punches!