Explain the basics of how volcanoes erupt; a volcano has an opened top that feeds to a pool of molten rock below the earth's surface. Detail how pressure builds up below; elaborate on how the lava is forced through the surface of the volcano, sending ash, lava and other debris to the mountain's surroundings. Tell children that especially destructive volcanoes destroy the land surrounding the mountain, often leveling forests and sometimes nearby cities; the most dangerous area is within 20 miles.
Teach how volcanoes are formed. Explain that small eruptions often form volcanoes over centuries, or sometimes they form in less than a day. Teach that magma from the Earth's upper mantle rises to the surface; it either pushes the ground up or erupts. The cooling magma becomes volcanic rock, forming the visible volcano.
Show pictures of the four different kinds of volcanoes. Explain that the "cinder cone" volcano is rarely higher than 1,000 feet above the ground surface and is formed by violent eruptions in which volcanic material lands around the cone. Teach that the "composite" volcano is the most noteworthy, reaching into the sky to become a mountain with several volcanic shafts. Include "Shield" volcanoes, which grow slowly over time and spread wide, and "Lava domes," which emit materials too thick to travel far.
Create a small volcano. Put a soda bottle in the middle of a baking pan. Pack moistened dirt around it, but leave the top clean. Put the baking soda inside the bottle. Mix the food coloring with the vinegar; pour the liquid into the bottle. Explain to the students that the two ingredients are creating pressure, causing the red liquid to escape through the top.