Young Adults

"What does the teenager *want* to do?"
Does this kid *want* to be HE-ed ... or does he just want to sleep & play computer games?!
Where does *this* kid want to go?
What are his strengths/weaknesses? (eg invest $ into strengths and perhaps less into other programmes if they are not key learning areas)

Motivation and Compliance

The teenager needs to see "the point". eg everybody does Maths & English, as "compulsory subjects", because they're the foundation - but maybe one child wants to study accounting & another chemistry, because of – their own - future plans.
No, they should be trained by now!
No radio on when doing school work, need disciplined studies at this age.
Use a student diary and let them plan their own work

How long do yours spend 'doing school'?

The older they are the more they do. They understand that more work (either schoolwork or housework) is a sign of growing up. Expect 5 "subjects", plus housework & family discussion time.
Morning and an hour or two in the afternoon for a teen

Have they jobs outside of their formal education?

Let them do a paper runs, or an "after school" jobs eg supermarket.
Volunteer
Give them a cv/ reference
'Pimp' your children ie get them to work for free

What age do you finish 'school'?

Let your goal be more "an adequate level of education" rather than finishing at a particular age. Eg all high school sciences, Calculus, general History/Geography, plus a decent amount of English.
Go for as long as possible to the degree needed for their chosen study or career path.

Is there any other advice on the high school years that would be helpful for our parents?

Give the teenagers some space & choices.
Get your husband to spend one on one time with your teen.
Get careers books out of library – useful to review and let young adults look through.
Give teens lots of down time, there's still plenty of time to be a grown up.