In her Back to School Stress-Management Toolkit for Teens, Melanie Greenberg suggests that one way to deal with school (or any other stress) is to distract yourself. The first part of this is to write a list of things that you can do to distract yourself. The second part is to do one of them. This engages the "on task" part of your brain instead of the "worry" part. The trick is to choose short activities that won't take too long. Avoid computer games, social media and netfix - they are sure to consume too much of your time.