The new reality series “Little People, Big World” (7 p.m. today, TLC) offers a documentary look at the life of parents Matt and Amy, two little people, just 4 feet tall, determined to raise their children and succeed in a world that doesn’t always accommodate their needs.

Matt is a software engineer who spent much of his childhood in the hospital undergoing painful operations to correct problems with his legs and joints arising from his inherited dwarfism. He’s determined to give his boys and girls the idyllic childhood of his dreams. Two of his children share their parents’ congenital dwarfism, and three are normal-sized. Amy has the no-nonsense demeanor of a busy mother and can be seen shopping for her kids, cooking meals and helping her kids cope with other students’ intentional cruelty or clueless rudeness. “Big World” would make for a very interesting one-hour film, but how many families can sustain our interest for 20 episodes?

¢ To honor the memory of the late Don Knotts, TV Land will kick off a 48-hour marathon of “The Andy Griffith Show” beginning at 5 a.m. today. I had the pleasure of interviewing Knotts some years back. He was justly proud of his participation in three hit TV shows: “The Steve Allen Show,” “Griffith” and “Three’s Company.”

¢ Decades before Diana and Charles filled the tabloids with tales of diva behavior and royal dysfunction, England’s Princess Margaret scandalized her society with her brazenness. Lucy Cohu (“Gosford Park”) stars in “The Queen’s Sister” (7 p.m. Sunday, BBC America), a profile of Margaret from the 1950s through the 1970s, when she aged rather gracelessly – careening from a forbidden love to a bad marriage to a series of affairs, a stint in a commune and at least one sordid night of rock ‘n’ roll debauchery.

l Jon Stewart hosts the “78th Academy Awards” (7 p.m. Sunday, ABC). The selection of Stewart has generated more chatter than the Oscars themselves. Hosting a show with a potential audience of 40 million viewers presents both a gamble and a remarkable opportunity for Stewart, whose “Daily Show” averages about 1 million viewers nightly.

Today’s highlights

¢ Sarah Silverman hosts the “21st Independent Spirit Awards” (4 p.m., IFC). A tape of the awards also will air at 9 p.m. on AMC.

¢ Russell Crowe and Jennifer Connelly star in the 2001 drama “A Beautiful Mind” (7 p.m., ABC).

¢ Natalie Portman hosts “Saturday Night Live” (10:30 p.m., NBC), featuring musical guest Fall Out Boy.

Sunday’s highlights

¢ Scheduled on “60 Minutes” (6 p.m., CBS): out-of-control hospital costs; a soldier held in two detainees’ deaths; Canada’s marijuana-loving Johnny Appleseed.

¢ Scheduled on “Dateline” (6 p.m., NBC): two men held for the murder of their brother, a small-town entrepreneur.

¢ The world’s surliest sock puppet gets his own showcase on “The Best of Triumph the Insult Comic Dog” (10 p.m., G4).