Here are sites where we read about volcanoes:

http://www.nsf.gov/nstw_questions/eart/quest083.htm
http://www.geosc.psu.edu/~jrogie/ans11-3.html
http://www.volcanoworld.org/
http://pubs.usgs.gov/publications/msh/contents.html
http://pubs.usgs.gov/publications/msh/continuing.html
http://www.volcanoes.com/
http://www.geology.sdsu.edu/how_volcanoes_work/Home.html http://www.volcanoworld.org/vwdocs/movies/movie.html
http://www.volcanoworld.org/vwdocs/eruption_scale.html
http://yahooligans.yahoo.com/content/science/brainpop/movie?id=volcanoes

http://wrgis.wr.usgs.gov/fact-sheet/fs169-97/