Sigrid uses common household objects to explain two ways to pronounce the letter A.

Sigrid explains a third way to pronounce the letter "A." For the first two ways, see Sigrid explains: the letter A - Part 1 of 4.

Sigrid explains that "A" is also a very important one-letter word.

We're finally at the end of the letter "A." Sigrid talks about the unstressed sound of "A" in words, and gives us some examples. For other pronunciations, see parts 1, 2, and 3.

Sigrid looks at the letter "B" as followed by either a vowel or a consonant, and the sound of the double "B" as well.

Sigrid finishes telling us about pronouncing the letter "B." Here's part 1 in case you missed it.

Sigrid explains about the "hard" and "soft" sounds for the letter "C."

What does the Holocaust have to do with us, anyway? In part one, Roderick Miller, the chair of the nonprofit organization Tracing the Past, gives a talk at TEDxVienna about the Holocaust and contemporary Europeans' perception of the space they live in.

What does the Holocaust have to do with us, anyway? In part two, Roderick Miller, the chair of the nonprofit organization Tracing the Past, gives a talk at TEDxVienna about the Holocaust and contemporary Europeans' perception of the space they live in.

What does the Holocaust have to do with us, anyway? In part three, Roderick Miller, the chair of the nonprofit organization Tracing the Past, gives a talk at TEDxVienna about the Holocaust and contemporary Europeans' perception of the space they live in.

What does the Holocaust have to do with us, anyway? In part four, Roderick Miller, the chair of the nonprofit organization Tracing the Past, gives a talk at TEDxVienna about the Holocaust and contemporary Europeans' perception of the space they live in.

When you listen to music, multiple areas of your brain become engaged and active. But when you actually play an instrument, that activity becomes more like a full-body brain workout. What's going on? Anita Collins explains the fireworks that go off in musicians' brains when they play, and examines some of the long-term positive effects of this mental workout.

Over the course of human history, thousands of languages have developed from what was once a much smaller number. How did we end up with so many? And how do we keep track of them all? Alex Gendler explains how linguists group languages into language families, demonstrating how these linguistic trees give us crucial insights into the past.

Romantic chemistry is all about warm, gooey feelings that gush from the deepest depths of the heart... right? Not quite. Actually, the real boss behind attraction is your brain, which runs through a very quick, very complex series of calculations when assessing a potential partner. Dawn Maslar explores how our five senses contribute to this mating game, citing some pretty wild studies along the way.

For the video for her song "Bad Blood," Taylor Swift had many of her famous friends make cameos. Their work paid off - it won video of the year at the 2015 MTV Video Music Awards!