President Obama speaks at the National Defense University in Washington on Monday. Since his re-election four weeks ago, Obama is showing signs of a new, more aggressive leadership style. Charles Dharapak/AP hide caption

LeVar Burton and 7 year old Shane Ammon exploring the all Reading Rainbow adventure app at the "Reading Rainbow Relaunch" event in June. AP hide caption

A stray cat rests at the Torre Argentina ruins in Rome in October. Officials say a cat shelter that sits adjacent to the site must be shut down. Filippo Monteforte/AFP/Getty Images hide caption

A Syrian rebel walks past the stairs of a bombed building in the Saif Al Duli district in Aleppo, Syria, on Sept. 10. The vast majority of those fighting against President Bashar Assad's regime are ordinary Syrians and soldiers who have defected, but Islamist rebels are also present among the fighters. AP hide caption

The largest tax break in the federal code doesn't appear on the forms the average person fills out each year. iStockphoto.com hide caption

The mushroom cloud of the first atomic explosion at Trinity test site in the southern New Mexico desert on July 16, 1945. AP hide caption

The $100 guitar proves once again that it's not just the instrument, it's what you do with it. Courtesy of The $100 Guitar Project hide caption