In recent years, we've seen an increase in the intensity of tropical storms and hurricanes due to global warming. But how and why do hurricanes form? Sigrid provides a basic explanation of this phenomenon.

We continue to explore the phenomenon of hurricanes. Why are they so dangerous? And do they serve any purpose?

Columbus Day has always been a controversial holiday in the United States. In this video, Sigrid goes back in time to get some historical background, which sheds a new light on its significance.

Most Americans don't realize how Columbus Day came to be a national holiday, but it actually doesn't have that much to do with Christopher Columbus, and we might even recognize a connection to present-day events. To recall something Mark Twain once supposedly said, "History doesn't repeat itself, but it often rhymes."

The European Union has been in the news a lot lately, so let's take a look at what it's all about. What is a "union" and what's the purpose of this one?

Bob Marley's universal appeal, impact on music history and role as a social and political prophet is both unique and unparalleled. This film documents the definitive life story of the musician, revolutionary, and legend, from his early days to his rise to international super-stardom.

This video is a Webby Award winner. Amnesty International supporters have used the power of words to demand freedom and justice for countless human rights defenders around the world. Our words are proof that when you stand up for human rights, you never stand alone.

Recently as a Save the Children Ambassador, Julianne Moore visited one of the poorest, most remote communities in the mountains of Appalachia in rural Kentucky where Save the Children has worked for more than 75 years.

They can flow like a liquid and bounce back like a solid. Masses of fire ants show a duality that intrigues physicists.

Doreen Cruz from Little Shop of Crafts in New York explains to us how her workplace functions as a creative outlet for both children and adults.

Sigrid explains the religious significance of Easter and the various days of Lent. Why do people observe Good Friday, or celebrate Mardi Gras? Find out in this video.

Easter eggs are commonly associated with Easter. Let's have a look at why that is, and what traditions have emerged.

Ever year, the winter solstice comes on December 21 in the Northern Hemisphere. Not only is it the first day of winter, it's a turning point, as the days will then get longer.

Sigrid talks about two important US holidays, Memorial Day and Labor Day. They are quite different in what they commemorate, but they're combined here because many Americans see them as bookends to the summer season.

What do people traditionally do on Memorial Day and Labor Day? Let's find out.