Georgian-British singer-songwriter Katie Melua sings her lovely song "The Walls of the World."

When Penny returns from visiting her family in Nebraska, Leonard is happy to see her. Sheldon, however, is much less welcoming when he learns that her family has the flu.

Miss World 2013 Megan Young from the Philippines continues her tour of London!

Mark King of the band Level 42 is a tourism ambassador for the Isle of Wight. Here he explains why.

The great white shark and killer whale are both infamous marine predators. Normally they leave each other alone, but one day, biologists off the cost of California witness something unprecedented.

More stunning footage from Alaska shows, up close and personal, the brown bears in action - hunting for salmon and caring for their young. Enjoy!

With the Rainforest Alliance certification, everyday purchases can help prevent deforestation and climate change, protect wildlife, alleviate poverty and transform business practices. Choose products with the seal of the green frog when purchasing coffee, cocoa, tea, flowers, fruit, paper, and wood products.

In summer, mother bears and their young cubs can be spotted on the plains near Hallo Bay in Alaska's Katmai National Park.

Learn about the states of matter, solids, liquids and gases, how they're different and where they're found in everyday life.

In this final installment of the series, a white Kermode bear encounters a black bear while fishing. Observe their behavior. Look and see for yourself what ensues!

On stage at Cannes Lions, game designer and author Jane McGonigal showcased research demonstrating the power that gaming can have in the real world.

Here in part two David Gallo shows more amazing footage of incredible undersea creatures. Enjoy!

In this first of two segments, learn valuable information regarding bottled water: its origin, its marketing to the masses and its effect upon our environment.

London born cellist Desmond from the YouTube Symphony Orchestra was flown to Australia and partnered with Sydney based country folk singer Luke Webb for a unique musical experiment. Their challenge: to collaborate and produce a piece of music influenced by their journey across Australia.

Hunger Games star Jennifer Lawrence discusses the end of the franchise, her hilarious relationship with Josh Hutcherson, and much more.