Stand Up to Cancer (7 p.m., Channels 2, 4, 5 and E! ): See accompanying story.
Are You Smarter Than a 5th Grader? (7 p.m., Ch. 13): The two-hour season premiere.
Stargate Atlantis (8 and 10 p.m., Sci Fi): Teyla goes undercover aboard a Wraith hive ship.
Swingtown (9 p.m., Ch. 2): In the season finale, the couples face decisions that could change their relationships. Actually, given the show's weak ratings, this is probably the series finale.
Samurai Girl (9 p.m., ABC Family): This three-part, six-hour miniseries, which continues Saturday and Sunday, requires you to disengage your brain, sit back and enjoy. It begins with a Japanese heiress's wedding being invaded by killer samurai, who murder her fiance. It's a big soap opera filled with action scenes, but it's entertaining in a dopey sort of way.
Dogtown (10 p.m., National Geographic): In the second-season premiere of this series about the Best Friends animal shelter near Kanab, dogs rescued from Michael Vick's dog-fighting operation are rehabilitated.
Monk (10 p.m., USA): In the series' 100th episode, Monk is being followed by cameras as he works on a serial-killer case. Former guest stars Howie Mandel, Andy Richter, Sarah Silverman and John Turturro return.