In order to reduce stress and anxiety, you need to locate the trigger, take breaks from technology, think of what you have done that is positive, and take a breather/walk. By doign this and living a healthy lifestyle you will better your stress levels and be less anxious.
Depending on the severity of the case, punishments from getting a zero on the assignment & the parents getting contacted (which is almost always the case), to failing the class, suspension, and even expulsion.
I hope that I helped you and that this is never the case for you - good luck!