Your children will begin to individuate and make their own decisions, like choosing their course work, becoming involved in sports or clubs, and seeking their identity based on those choices. This is where we as parents need to learn to let go. Micromanaging or helicoptering your children does not help them -- it actually harms them.
So, to the young woman who finds herself in this moral dilemma of shall I or shall I not, I say unto you, "just don't." If your grade is impacted - all will be well. You'll find that in life you will experience many more situations that will require you to abstain, even at the risk of some negative consequence.
My kids are well liked by their peers. They're socially adept and smart. But when given the choice of chasing a kid up a hill, or sitting with my wife and me on a park bench, they choose us. Even when their friends are begging them to play. They might occasionally run off with another kid for a few minutes, but they're not gone for long.
The goals of a free-range parent are the same as those of most parents: to raise their kids to cope successfully with life, and if possible, be outrageously happy. Humans have been debating how to get your kid to be a successful adult since we began to speak. For free-range parents, the answer is autonomy and responsibility -- early and often.