Sigrid explains what cardinal numbers are and gives us some writing and pronunciation tips.

Sigrid finishes the alphabet with "Z," covering words like "zone" and "zebra," but also the useful suffix "-ize."

Anna, from Cambridge University Press, explains how and when to use the Present Simple.

"Y" is a tricky letter because it's both a consonant and a vowel. As a vowel, it has different sounds. Don't worry. But hey, maybe keep your eye on the "Y." Don't let it fly away.

Gabrielle presents three key questions you're likely to face when being interviewed for a job. Her advice is spot on.

Do you want to prepare for that big job interview? If so, take a look. Gabrielle offers some valuable information and a few helpful hints.

"X" is a special letter in that we often use it by itself. It's useful in a lot of situations. In the middle of a word, however, it can be pronounced in a few different ways.

"W" is a consonant, but it is very vowel-like and is considered a "semi-vowel." "W" is featured in plenty of important words, and it combines with other letters to make some new sounds.

"V" is a voiced consonant. "Voice" starts with "V." We make the sound with the upper teeth lightly touching the lower lip, like "F" but with the voice, too. It vibrates. The verb "to vibrate" also starts with "V." That should make it easy to remember.

"U" is an interesting vowel, and has a few different sounds. It can even sound like the consonant "Y," and combines with other vowels to make new sounds.

Fuse School: Learn the basics about the effects of global warming on the environment. Some of the problems global warming may cause are changing climate, extremes of weather, problems for ecosystems, rising sea levels, and ocean acidification.

Annette sharpens her skydiving skills in a vertical wind tunnel in Slovakia. The wind reaches a speed of 180 kilometers per hour (112 mph).

Sigrid gives a quick explanation of what Yabla is and how the Yabla player works.

This is a public service announcement of the Obama administration on ending sexual assault. President Obama is joined by Vice President Biden, Daniel Craig, Benicio Del Toro, Dulé Hill, Seth Meyers and Steve Carell.

Annette explains three more colloquial contractions people use in everyday conversation: gotta [got to], gotcha [got you], and dunno [don't know]. She also gives us examples in context.