What does he have to say about his behavior? That is the question.
ask him point blank, why are you lying about attending school?
Get approval... Start attending school with him. You drive him, walk in with him. . Go to all of his classes. Sit through them. Sit with him at lunch..
Do this every day. Let him know that if necessary you will continue to do this, until he can prove he will go on his own.
Is there an alternative school for him to attend?
here in Austin, oncce a student has so mnay hours, they are allowed to attend the alternative high school. They study at their own pace. They will not have to take all of the extras like in regular high school. They go on their own schedules.. many finish up and are able to graduate early. This allows them to either start college earlier or get jobs..
Could be your child is just done with the whole school thing.. He just needs to complete the studies and move on..