Star Tracks - Tuesday, September 9, 2008

Now a junior in high school, Miley Cyrus makes a pit stop at an Office Depot in Los Angeles to buy school supplies on Monday with mom Tish (not pictured). What's the 15-year-old Hannah Montana star's favorite subject? "Math because there's always a right or wrong answer!" she told PEOPLE.

See more stars getting ready for school.

Jessica Simpson has tongues wagging Tuesday morning during her performance on Good Morning America from New York's Times Square. The singer, whose country album Do You Know hit stores the same day, performed her new single "Come On Over" and her hit "With You," which she had to start over after a technical glitch.

Victoria Beckham debuts a chic, cropped 'do and a new pal – the equally stylish Jennifer Lopez – on their way into the Marc Jacobs runway show Monday during Mercedes-Benz Fashion Week in New York. The pair soon took their front row seats at the New York State Armory – then headed to dinner together at Cipriani after the show.

Catch up with all the stars at Fashion Week.

Watch out Posh amp J.Lo! Nicole Richie and Jay-Z make another interesting duo (and new friend match) at the Marc Jacobs fashion show Monday in New York.

Back from the Toronto Film Festival, Jennifer Aniston supports friend Courteney Cox Arquette Monday at a New York Fashion Week launch of Propr, husband David Arquette's fashion line with musician pal Ben Harper.

See more stars making the Fashion Week scene!

It's Matt in the middle! Proud dad Matt Damon joins members of the African Children's Choir Monday at the OneXOne charity gala in Toronto, Canada. The actor, who hosted the event to fight child poverty, told PEOPLE that almost-3-week-old daughter Gia Zavala is already smiling.

Mark Wahlberg gets some bonding time in with 5-year-old daughter Ella Rae at the Grove shopping center in Los Angeles. Among their stops: a trip to the American Girl Place. The actor, who also has 2-year-old son Mike with girlfriend Rhea Durham, has baby No. 3 on the way.

We'd love to be in on that joke! Star Jones and Anne Hathaway share a laugh Monday during the U.S. Open men's single final between Roger Federer and Andy Murray in Flushing Meadows, N.Y. Besides laughing it up, the ladies watched Federer win his fifth straight U.S. Open title.

Ashton Kutcher and wife Demi Moore add a dose of celebrity to the TechCrunch 50 conference, attending a VIP dinner at San Francisco's Design Center on Monday. At the conference, the actor unveiled his latest project, a new celebrity culture Web site called Blah Girls and met with MySpace CEO Chris DeWolfe.

Nicole Richie gives daughter Harlow – who turns 8 months old on Sept. 11 – a view of the Big Apple during a stroll through the city on Monday. Richie recently announced plans to launch an online gift registry to provide baby products to mothers in need.

That's a point deduction! Ellen DeGeneres struggles to stay steady on the balance beam under the watchful eye of Olympic gold medalist Shawn Johnson during a recent taping of her talk show in Los Angeles. The episode airs Sept. 9.

Talk about bouncing back! Only two months after the birth of daughter Sunday Rose, a glam Nicole Kidman is back to her pre-baby shape Monday while attending the National Movie Awards with husband Keith Urban (not pictured) at the Royal Festival Hall in London, where she's rehearsing for the movie musical Nine.

Following her appearance on Friday's star-studded Stand Up to Cancer charity event, Halle Berry steps out with boyfriend Gabriel Aubry and their 5-month-old daughter Nahla for a retail rendezvous Monday in New York City.

Now that's an arresting appearance! U.S. Open tennis champ Serena Williams takes her trophy out on the town Monday, modeling atop a police cruiser in New York's Times Square.

After supporting her brother at his photography exhibition, it's back to basics for Naomi Watts, who shows off her baby bump while running errands with a friend Monday in New York City.

Kristen Bell and boyfriend Dax Shepard are all wrapped up in each other Sunday as they take a dip while on vacation in Hawaii. The Heroes actress heads back to the small screen when the NBC show returns on Sept. 22.