For people who have demonstrated a failure in personal finance or are really financially illiterate (most 14 to 22 year olds?) I'd start with the concept of a budget- How much money do you have coming in, where is it going to go, how to stick to it (write it down, cash method, checking receipts against budget, mint?) Then, I'd move on to interest- for and against you: Showing a savings account, the market, and a credit card over 1 year/ 5 years/ 10 years/ 30 years. Then- Free money- pre-tax accounts for retirement, employer matches. Activity: Budget- income of $3,000 a month, employer match to 3% of 401K, 1 person, with options for housing, food, transportation, spending. OR online game: "Spent" about minimum wage.
Assuming that because these are professionals, I think you might want to leave out budget and credit cards and savings accounts, and start with the market. How to minimize fees/ maximize stability and returns, and then "Free money." I think the most mustachian thing could be to discuss how your home might be an asset, and if you buy an expensive one, and can't invest in the market your portfolio is out of balance. Or, your home can be an expense, but then you shouldn't be thinking of it as an asset. Maybe also how to determine "what you can afford" in a house you are buying (probably better targeted at younger professionals rather than older).
Activity: if it's a workplace, hand out the forms for the 401K and do the math on your policies.