There's one more important question word to learn: "how." Sigrid provides plenty of examples of questions with "how," both by itself and together with an adjective or adverb.

Sigrid packs her carry-on bag for the flight to Paris. She talks about what she needs to pack, and why.

We use question words plus words like "some" and "any" to form new indefinite words, such as "sometime," "sometimes," and "anytime." This video is about question words "who," "what," and "when."

This video is about indefinite answers to the question words "where" and "how." We combine these question words with "some" and "any" to form new indefinite words, such as "somewhere," "somehow," "anywhere," "anyhow," and "anyway."

With longer adjectives, we have to add some extra words in order to form the comparative and superlative. Sigrid explains how.

Every modal verb is a bit different and not all of them can be used in all tenses. We use "may" for permission, but we can use "can" and its conditional form "could" as well.

When do we use "should" and "could"? At the end of the video, you'll also find a preview of the next 2 videos where modals are used in everyday speech for discussing probability.

Sigrid has lost a couple of important items and is trying to think where they might be. In this part, she has lost her car key. She uses plenty of modal verbs to tell her story, including modal verbs expressing probability.

Now Sigrid has also lost her glasses! In this final part, learn how to use modal verbs to express probability, and find out whether she finds the missing items.

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

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

In this segment, the narrator explains where the name Bryce Canyon came from, and why the sand dunes in the US and the large deserts of the world might be related.

The narrator explains how the breathtaking rock formations of Antelope Canyon came to be, and why mountains around the world can provide a metaphor for human existence.

This song teaches about the digit 0, portrayed as a superhero, as well as multiplication by powers of 10. This song was voted the 11th best song on the 30th anniversary edition. Sung and written by Bob Dorough.

In American schools, it's common for kids to have to learn the Preamble to the United States Constitution by heart. This song, from Schoolhouse Rock, is meant to give these kids a hand, even though it is a slightly abridged version.