Joseph Arradondo assists his son Nasir, 2, on the sidelines of his daughter's soccer game in Brooklyn Park, Minn. Arradondo attended Co-Parent Court about a year ago and says the court helped with communication between him and Nasir's mother. Jeffrey Thompson/MPR News hide caption

Studies say just 30 minutes of walking a day can reduce several lifestyle diseases many Americans are living with. iStockphoto.com hide caption

Researchers say our brains are probably wired from an evolutionary sense to encourage running and high aerobic activities. Above, a man runs past the Sydney Harbour Bridge on April 22. Ryan Pierse/Getty Images hide caption

Facebook founder Mark Zuckerberg speaks in a video that is part of the company's prospectus for investors. By remaining a privately held company, Facebook has helped boost the popularity of secondary stock markets. NPR hide caption

Khalid Sheikh Mohammed and four other defendants accused of the 9/11 attacks refused to cooperate when they went before a military commission in Guantanamo Bay, Cuba, on Saturday. AFP/Getty Images hide caption

In this photo taken June 14, 2011, a damaged sign for Joplin High School (transformed into "hope" with tape) is seen in front of the school. The school was one of three in the city destroyed by an EF-5 tornado that wiped out much of the community. Charlie Riedel/AP hide caption

Released in December, Carly Rae Jepsen's "Call Me Maybe" has been rising on the charts — it reaches no. 5 this week — and winning the hearts of fans on YouTube. Vanessa Heins/Courtesy of the artist hide caption

Sen. Ted Kennedy, D-Mass., and Republican challenger Mitt Romney (right) take part in a televised debate at Holyoke Community College in Holyoke, Mass., in 1994. Romney lost to Kennedy in his first political race. Charles Krupa/AP hide caption

Artist Daniel Clowes says Enid, the cantankerous heroine of Ghost World, would probably hate the book she stars in. Daniel Clowes/Oakland Museum of California hide caption