Why are some rock formations and animals found on more than one continent? The explanation dates back to the Ice Age.

Why do some of the national parks in the United States resemble the European Alps? Geologist Dr. Robert Darga answers this question.

Here's the trailer for an inspiring film about the efforts of ordinary people to make the world a more sustainable place. Experts talk about the necessity of taking action.

Who knows when we'll discover whether we are alone in the universe or not? Whatever the answer, the quest for more knowledge will never cease, nor grow dull.

Bohemian Rhapsody is a biographical film about the British rock band Queen, focusing on lead singer Freddie Mercury's life leading up to Queen's Live Aid performance at Wembley Stadium in 1985. Freddie defied stereotypes and shattered convention to become one of the most beloved entertainers on the planet.

Catch up on winter vocabulary with Sigrid. It's also a great chance to practice words with "W," since there are plenty associated with winter.

Hindi-English, Chinese-English, and Singaporean-English are discussed and we're introduced to some fun words, such as “badmash” (noun, a bad person in Hinglish) or “chope” (verb, to set aside a place in a fast food restaurant by setting down an object like a hankie or magazine in Singlish).

We can use nouns, verbs, or adjectives to describe someone's personality. Sigrid shows us how to describe someone with a strong personality.

Here's how to pronounce a very important noun with an unusual plural!

True possessive pronouns can stand alone. They replace both the noun and its possessive adjective or determiner. These pronouns are very handy in introductions and conversations about favorites.

Plastic pollution poses one of the biggest known threats to the ocean and all related ecosystems. Pollution comes in many forms, and agriculture is one important key to bringing about necessary change. All of us are key players, since we all eat food.

Sigrid takes us through the different persons using dependent possessive pronouns, also called possessive adjectives or possessive determiners. These little words are important when talking about names, your possessions, family and friends, characteristics, jobs, favorite things and just about everything else.

Sigrid talks about the difference between possessive nouns and other possessive words such as possessive determiners or articles like "my" and "your."

Sigrid reviews the object pronouns: "me," "you," "him," "her," "it," "us," "you," and "them."

Sigrid reviews the subject pronouns "I," "you," "he," "she," "it," "we," "you," and "they."