I can’t talk in class
It is invaluable to your work as a student, your homework, paper writing, research, and professional development all depend on your ability to make professional connections and engage with the subject matter. You can get better by being yourself; you don’t need to turn into someone else. If you only speak once a term, then it’s time to make the goal, speak once in every class. Get in the habit of doing things at least one small measure better than you usually do them and you will find yourself growing academically and professionally from there.