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

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.

Let's have a look at which countries are members of the European Union and where they are on the map.

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?

This animated video shows how tuberculosis, still a very common disease, spreads and is fought by our bodies. Find out more about MSF’s work treating tuberculosis around the world.

They may have very different reputations, but both the great white shark and killer whale are fierce predators that face off in a showdown atop the ocean food chain.

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

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.

Sigrid explains how a spelling bee normally proceeds. There are fixed rules and there are options.

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.

Jonathan gets back to filming so that Neal can show off his skills as a shark handler. He controls the big sharks through various maneuvers, including his ultimate demonstration: holding a shark vertically using only one arm—almost like a shark headstand!

Sigrid talks about "The Elementary Spelling Book" by Noah Webster, which was the basis for the American English dictionary and a big part of the development of spelling bees in the United States.