We're required to notify parents of any senior who may not pass our classes and, hence, is "in danger of failing". Of my 90 or so seniors, 5 are in danger of failing.
The devil, though, is in the details. In my statistics classes the final exam counts for 20% of a student's overall grade. Thus, any student going into the final exam with a grade under 75% has a mathematical possibility of failing. If I remember correctly, though, 4 of those 5 have grades between 70 and 75%, which means they would have to score less than 20% on the final exam in order to fail the course.
But I still had to send out those emails today, to the dismay of the parent who emailed me back almost immediately.