Chronicling America, from the Library of Congress, is a site that contains a huge database of historic newspaper pages from the years 1836 to 1922. Their homepage features "newspapers from 100 years ago today" but users of the site can use their extensive search option to look for year, state, topic, newspaper, dates, and even language. Here is a clip from a newspaper when I searched "World War I, New York, 1918."
Chronicling America could be a good tool for student research from a particular era or topic. If you are a history teacher you owe it to yourself and your students to take some time to browse around and see what the site has to offer.