The school year and the third season end on “Friday Night Lights” (8 p.m., NBC), the wonderful, documentary-style series with a small but committed audience.

“Lights” remains one of the handful of series dedicated to the idea that ordinary life can be the stuff of powerful drama and that there are great things at stake in everyday events like starting a business, receiving college acceptance letters and buying a bridesmaid gown. It’s one of the few dramas that does not revolve around the supernatural, crime, police procedures, mortuary techniques, sex between interns or murder.

Tonight’s “Lights” was obviously completed before the decision by NBC and Direct TV to renew the series for another two seasons, so it has the air of a possible finale about it. Many of the series regulars are going off to college, and coach Taylor (Kyle Chandler) finds his job in jeopardy.

We’re in valedictory territory because almost all of the teens end up doing and saying the right thing just when it matters. That’s a tad too noble to endure or believe on anything less than a series finale.

As on any drama or romance in search of resolution, we find ourselves at a wedding reception by episode’s end, a sprawling and casual party captured in fits and starts by hand-held cameras. The band is less than stellar and not everybody dances well or looks like they’re having a good time. It’s a beautiful scene and a reminder that “Lights” is one of the most cinematic, ambitious and grown-up series on television.

• “Patton 360” (8 p.m., History) offers military history buffs a 10-episode series dedicated the World War II battles of George S. Patton, one of the most colorful and controversial leaders of the war. “360” presents military history though the eyes of men (now in their 80s) who participated in Patton’s campaigns, as well as commentary from contemporary soldiers and strategists. Period footage is complemented by historical re-enactments and computer graphics.

The result is a remarkably thorough approach. Hour one involves Patton’s invasion of Morocco, a three-pronged attack on the French defenders of Casablanca.

This hour-long series debut covers events that take place well before the beginning of “Patton,” the 1970 screen biography starring George C. Scott.

• Diane Sawyer hosts a special report on “20/20” (9 p.m., ABC) “If I Only Had A Gun,” a look at our society’s relationship with firearms, fear and violence.

Tonight’s other highlights

• The Connors confront Weaver on the season finale of “Terminator: The Sarah Connor Chronicles” (7 p.m., Fox).

• Second-round play from The Masters (7 p.m., ESPN).

• An emotionally unstable couple kidnaps the baby they put up for adoption on “Flashpoint” (8 p.m., CBS).

• Echo tries to find a traitor in their ranks on “Dollhouse” (8 p.m., Fox).

• Evidence points to zealots behind a scientist’s slaying on “Numb3rs” (9 p.m., CBS).

• A wrinkle in time lets dinosaurs walk among us in the repeat first season of the British fantasy “Primeval” (9 p.m., Sci Fi).

• Bernie Mac and Ashton Kutcher star in the 2005 comedy “Guess Who” (9 p.m., TNT), an update of “Guess Who’s Coming to Dinner.”