Volcanoes are one of Earth's most fascinating and destructive forces. In Volcanoes, students will get an up-close look at these fiery formations, discovering how they form and what causes them to erupt. Learn the difference between magma and lava, and discover the characteristics that enable volcanologists to classify a volcano as cinder cone, shield or composite. Examine the anatomy of an active volcano, and learn about historical eruptions that have left a mark on our planet. A fun, hands-on investigation demonstrates how a tilt meter is used to predict when a volcano might erupt by charting changes in the slope of the surrounding ground, while a visit to Horseshoe Lake at Mammoth Mountain, California, highlights an invisible sign of volcanic activity -- poisonous carbon dioxide fumes. Part of the Earth Science in Action DVD Series. A teacher's guide is available online. 23 minutes. Grades 5 to 8.