Once the kids were about 9, we started including stories about the Declaration of Independence - focussing on the dedication and earnestness of the men who faced the dire problem of tyranny and created a solution which we still benefit from today.
At about 11, we included movies like the wonderful "1776", and others I don't remember now - again, not adult movies which focus on the war scenes. And we spent the 8 minutes it takes to read the Declaration of Independence, with the 10 minutes it takes to talk about what different passages mean. ... After seeing "1776", the kids were very interested to get a look at this Declaration of Independence for themselves !
Then when they were in 8th grade, we added reading the Preamble to our US Constitution and talking a little about what is in it - just as talk around the dinner table during the 4th of July weekend.
It made the holiday much more special for the kids !
at 2:29 PM on Jul. 3, 2009