I'd almost like to do a trifold specifically for the 18-21 year old bracket.
Few people in that age range realize that by Michigan law, they can purchase a handgun and carry it for self-defense purposes.
Also, for this age range, I'd really focus on:
1.) General firearms safety
2.) Brief history, design, and function of common firearms
3.) Discuss target shooting (Bench, Biathlon, IDPA/IPSC)
4.) Discuss hunting
5.) Self-defense, importance of firearms (slate this more towards the older kids)
Mind you also, that any excursion even near a shooting range, will require a safety waiver and parental consent for those under 18 years of age.