Spanish History Poems

Help with Collins "Billy The History Teacher"?
Beyond the humor of the poem, what meanings can discern serious? Professor history – Billy Collins Trying to protect the students, "the innocence of his told the Ice Age was really only the Age of Charly, a period of one million years, when everyone had to wear sweaters. And the Stone Age became the Gravel Age, the name of the access roads over time. The Spanish Inquisition was only an outbreak of questions such as "How far is it from here to Madrid?" "What do you call the matador's hat?" The War of the Roses took place in a garden, and the Enola Gay dropped one tiny atom on Japan. Children left his classroom to the playground playground to torment the weak and the smart, mussing her hair and breaking their glasses, as he gathered his notes and went past beds of flowers home and white picket fences, wondering if he would believe that soldiers in the Boer War told long, rambling stories designed to make the enemy off gesture.
The poet lets us see the teacher as a harmless eccentric. He is immune to tragedy and is a cartoon character for children as he sees only good in the To protect your innocence. The serious message is that he sees no potential evil in their students. The Gestapo little play area are preparing for a future time when they can also commit crimes against humanity.