Though I don't encourage showing an unguided movie in class, I do encourage the use of a film like John Adams to enhance the learning. That said, Part 1, entitled 'Join or Die' contains an excellent portrayal of the Boston Massacre and all of the indecision and doubt that surrounded the trial. For about minutes, HBO took you through the "riot", the reaction from the Colony, the decision for Adams to defend Captain Preston and the soldiers and finally the trial.
Done succinctly and with very little off topic tangents, it would be of good use in a US History class discussing the Boston Massacre and how it catapulted Adams into the spotlight and further ripped the seam between the Colonies and the King. It would also serve the purpose of a government class, exemplifying the "innocent until proven guilty" mantra as well as the emphasis of "facts and evidence" as clearly stated by Adams.
In addition to the Boston Massacre, part 1 alludes to the Boston Tea Party, the Intolerable Acts and concludes with Adams being selected to attend the First Continental Congress in Philadelphia.
Here is HBO's recap of episode one: http://www.hbo.com/films/johnadams/. It's cool and interactive. Heck, use this in class. Then show bits of the film. If you've got a DVD recorder show it now... it's for education... copyright? bahumbug!!!
Laura Linney is great and the guy who plays John Dickinson is impressive as well. George Washington, is played by the usually familiar face of David Morse (Green Mile, Hack), who incidentally was born in Massachusetts, Adam's "country".
If this film does anything it changes my perception of John Adams only in as much as how he looks and talks. I'm a big fan of the movie 1776, where Adams is portrayed brilliantly by William Daniels (aka Mr. Feeny from Boy Meets World, Dr. Craig from St. Elsewhere and of course... the voice of K.I.T.T from Knight Rider).
For your pleasure I've included an excerpt from 1776, to give you an idea of how I used to view John Adams... Paul Giamatti might just be good enough to change my mind. Can't wait for Sunday night.