By far the best advice I have for teens who are this age is to start taking college classes. I realize this might not be a good fit for everyone! But for literally every homeschool student I have worked with, this is what they did. And it was great.
Ok. So a couple questions you might have: 1. How do I have a 16 year old (or whatever age) take college classes? OR 2. College classes are NOT a good fit for my kiddo. What else can they do?
1. How to have a kid without a diploma take college classes (I am assuming you are in the United States for this):
a. Check with your state - lots offer college level (and college-credit-earning) courses through local high schools - some of this can be done online now.
b. Community/tech colleges - you can often enroll students as young as 14 in their online courses.
Note: to make things smoother get some kind of transcript together - it doesn't have to be anything fancy at all. I'll get some examples up here before too long!
Please read #2 below because these are good things for kids to try even if they are taking some college classes. Actually. They might be even MORE important than taking college classes?
2. What else is a good idea at this age besides college classes?
a. Volunteer. I think volunteering in itself is a wonderful thing at almost any age. But now that your teen is older, they can get seriously involved in an organization.
b. Work. Anywhere. Ok. I don't know about ANYWHERE. But I believe different sorts of job experiences are helpful - even if some of them aren't enjoyable.
c. Unpaid Intern. Gah. I have some mixed feelings about this idea because I think for-profit companies should PAY for work done. But, let's say your teen is interested in an industry that is SUPER competitive and getting a foot in the door somehow is going to be a real advantage, this might be something to consider.
c. Skill Development. There are so many options for learning just about anything online. If your teen can be intrinsically motivated to work consistently on something they would like to get good at: GREAT! Otherwise a more formal class is a good option for keeping them moving forward.
d. Deep Learning. This might be my favorite simply because I love learning for learning's sake. The great thing about learning a topic in-depth is that one starts to understand how much there is to know about ANY topic. A long period of in-depth focus on one topic doesn’t only help your teen know that topic, it helps them understand nuance, where there is consensus in the field, what is still contentious, how to recognize good evidence and arguments, and how to spot the bad.
(I am positive you are already thinking along all of these lines and that is a huge reason why you are choosing to have your older teenager continue to do school some other way than a traditional classroom approach! I would LOVE to hear what exactly your teen is doing! Send me an email - I read every one!)