Lot of pretty high-level suggestions here, which is fine. What about just a household budget? You can call it modelling a single family economic unit, if you need to make it sound fancier :)
One of the best things my mom did when I was a kid was sit down and model out a lifestyle. Poke through the classifieds for a job you could get with a high school diploma, find the price of an apartment for rent, find the price of a car, call up for an insurance quote. All that should be easy with the internet, but it forces them to realize that it's all realistic and not some arbitrary numbers.
Then make them take their individual scenarios and project them into the future. Are you going to be rich in 30 years, or broke in 5? Then make them stress test their model life: car problems, health issues, layoffs, etc. Talk about the financial consequences of different solutions to those problems - eg, going into credit card debt vs cutting spending, or using up savings. Maybe also model going to college instead, and figure out when the increased earnings break even with the upfront costs (including debt & opportunity cost).
With a little luck you teach them some good financial skills, make them think realistically about what's waiting for them after graduation, and get them to realize what a trap debt can be.