Bill Nye explains plate tectonics and the origination of its theory. The areas in which the tectonics spread apart is where volcanoes form. Conversely, the areas in which the tectonics come together is where mountains form.
Sabrina explains how the earth changes using seasons and landforms as examples. She illustrates how landforms form and change over time by mentioning plate tectonics, erosion, and weathering. She uses famous examples of gradual change (The Grand Canyon and The Old Man of The Mountain) as well as examples of quick change (Mount St. Helens) to stress that the earth changes in ways that are both noticeable and not so obvious.