<p>Well, if it is legal in his state, he could do it. Sticking one's neck out is brave but has consequences... and for a 17-year-old to do that is hard. I would have been outraged but told my son to hold his breath and stick it out.</p>
<p>Or to go to the school authorities after the school year is over and he has a diploma in his hand.</p>
<p>In most states, a parent can legally visit any class they choose at any time. Check on your school's policy. It's possible that just having a parent come in for a day---whether they understand fully what's going on or not---would cause the teacher to back off a bit. And if it doesn't, your parent can go to the principal and be smarmy: "Excuse me, I don't understand why class participation is so much of my child's grade. Can you help me understand that? And how does he earn those points? I see. I'm very concerned because I expect my daughter to earn all As."</p>
<p>Smarm has worked for me for years. You just keep asking extremely polite questions while the teacher digs a hole for him/herself. The extremely polite part is key.</p>