English is an expansive language, anyone who has seen the size of an unabridged English dictionary can tell you that. It's also a language that's ever changing and evolving, so of course there are some words that fall out of favor and are hardly ever used, but maybe it's time to bring some of them back!
Teaching Idioms? I know I'm preaching to the choir when I say that idioms are more fun than a barrel of monkeys. There is a boatload of idioms at GoEnglish.com. Beyond going over the literal meaning of such phrases as "It's raining cats and dogs!" there are many other out-of-this-world things to try. They are the cat's pajamas, so give them a whirl!
Can we bring this back?? < can I note the fact that in "Fantastic Beasts and Where to Find Them" (movie version) Queenie asked for six shots of Gigglewater for Jacob. Keep in mind that this took place in 1926