What are some concerning behaviors an educator should look for in students and how can these behaviors be recognized?

As educators, we must strive to be proactive in recognizing behaviors that might suggest a student poses a threat to the safety of other students.

What are some concerning behaviors an educator should look for in students and how can these behaviors be recognized? What steps can a teacher/school take to address these behaviors without unduly violating the student’s Constitutional rights? Could a teacher/school be held liable for negligence if they suspect a potential danger and take no action? Explain.