Hmm a toughie. I think you're doing the right thing in not forcing her. I wonder if a job would be the answer though, if she's struggling to apply herself? Maybe it'd just put schooling further off the agenda?

I had a part-time job during VCE and it put me under a lot of stress and pressure. I would have done a lot better in school had I had more spare time. I would sleep in and take days off school just to catch a rest (worked sat & sun). In year 10 it was fine and year 11 of little consequence, but my year 12 really suffered.

At the end of the day, her first job will teach her time management, responsibility, the value of money, etc, whether she starts it at 16 or 18, yanno? If she's not getting the most out of her education now, she'll get even less if she has to work, IMO. If she's sticking with school, she may as well get the most out of it.