Medieval Siege www.pbs.org/wgbh/nova/lostempires/trebuchet   Gr. 4-7. Learn about life inside a medieval castle. Build a trebuchet and knock down a castle wall! EyeWitness To History www.eyewitnesstohistory.com   Gr. 7 & up. Primary source materials on world history including Ancient History, Middle Ages/Renaissance, World Wars I & II, Civil War, Old West and 17th-20th Centuries. Listen to sound files of voices from the past.