After visiting Professor Marvel, Dorothy runs back home and finds that a tornado is threatening her house and family. Dorothy returns home and cannot enter the cellar because the barn keepers and her family have locked it. She enters the house, and is knocked unconscious by a shutter that comes loose off of a window in her room. This clip depicts the typical characteristics of a tornado.

The group explains the Fujita Scale to Melissa. They mention that the Scale is a classification for tornadoes based on the amount of damage they cause, and they give an example of the damage that would be caused by an F4 tornado.

Helen and Bill run away from an F5 category tornado. They consider taking cover in a nearby barn, but it contains a lot of sharp objects that make it unsuitable as a shelter. As they leave the barn, the tornado obliterates it.

Clark and his family head for cover as a huge tornado destroys everything in its path. Jonathan sacrifices himself to save the family dog.

Bill Nye explains what volcanoes are, how they're formed, and what causes an eruption. He then explains the impact of volcanoes on the earth's geography.