Volcanoes Poster, a double-sided poster dramatically illustrating the impact, structure, and types of volcanoes. Go to http://erg.usgs.gov/isb/pubs/teachers-packets/volcanoes/index.html for the online lessons, an interdisciplinary set of materials for grades 4-8, students will explore questions such as "What is a volcano?" "Where do volcanoes come from?", "Why do volcanoes erupt?", "Where do volcanoes erupt," "Can scientists forecast volcanic eruptions?" and detailed information on the eruption of Mount St Helens.