Whether you are teaching English, history, or even science, a rousing twenties party can be the perfect way to teach an era rich in significance. It is always better if teachers can coordinate their efforts when teaching, and make an event like this last the duration of one or two class periods. If a history teacher can teach about the twenties, organized crime, prohibition, the formation of the Nazi party, World War I or other twenties related history, while an English teacher covers literature such as The Great Gatsby, and a science teacher teaches chemical processes, they can combine their efforts to coordinate a party for their students.
Make this worth a grade, so each student will participate. Give credit for costumes, and let students choose to come as gangsters, flappers, or twenties gentlemen and women. Give the students just a little bit of background on the era, or allow them to watch movies set in the twenties, such as The Great Gatsby or The Cotton Club, and let them use their imaginations.
Have costume contests with the winners getting a prize and organize a classroom version of Jeopardy, where students are divided into teams, and choose an answer in one of the categories. The team winning the jeopardy game get a prize and the runners up get a consolation prize.
The biggest challenges will be to get the students involved. If you feel students won't come in costume, consider going to a local thrift store or consignment shop to talk to the manager. In most cases they will be glad to lend hats, feather boas, etc, to help students get into costume, and you can return them when the party is over. Another option would be to find twenties related photographs or pictures in magazines, cut them out, and let students free write about the twenties for extra credit.