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.

Enjoy another walk through the fields with pig brothers Piggeldy and Frederick. This time Piggeldy wants to know what a sheep is.

When Christy’s boyfriend shows up, Tommy is left in confusion and he needs to make a quick exit! He then has to visit the probation office, where at least he seems to be striking up a good rapport with his probation officer’s son.

It’s June, and Yosemite has come alive with noise and vibrant colors. The meadow flowers are in bloom, the bobcat kittens are almost full-grown, and the park’s unique amphibian and rodent populations emerge from their winter rest.

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.

The probation officer saves Tommy's job at Pirate Burger, and this time he’s entrusted to make a delivery. He uses the opportunity to try to make contact with Christy again.

In the lower valley, a foraging black bear attacks a colony of ants, which quickly rally to defend themselves. At its driest in summer and fall, the park is at the mercy of forest fires. One of the largest ever, the Rim Fire, broke out in the autumn of 2013, and burned out of control for over ten weeks.

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.

The production of the song "Now and Then" took place over five decades and is the product of conversations and collaborations between the four Beatles that go on to this day. The long mythologized John Lennon demo was first worked on in February 1995 by Paul, George and Ringo as part of The Beatles Anthology project but it remained unfinished, partly because of the impossible technological challenges involved in working with the vocals John had recorded on tape in the 1970s.

There’s a surprise in store when Tommy’s food delivery turns out to be for somebody he already knows.

Yosemite’s trees and animals have adapted to endure the occasional wildfire and the extreme changing of the seasons. In September, marmots prepare their burrows for hibernation and the deer are full of energy as the annual rut approaches.

Yosemite’s mountain peaks are already capped with snow and a mist rolls through the valleys. The coyote’s mating season begins as winter starts, and the bobcat mother will soon leave her young to fend for themselves.

Here are some verbs that are handy when plans change. This segment features "to postpone," "to delay," "to procrastinate," and "to put off."

Enjoy another walk through the fields with pig brothers Piggeldy and Frederick. This time Piggeldy wants to learn about “weeds.”

Tracy Chapman’s powerful song "Fast Car" tells the story of a young couple escaping their hometown in search of new opportunities, and of heartache, as dreams crumble along the way.