Collect evidence
We can collect evidence by audio or video recording as the basis for us to call the police or report problems to relevant departments. If there are illegal acts such as beating people, you need to go to the hospital for forensic identification in time and submit it to the public security department.
Record quietly
If we don't collect evidence in time, we can take other measures. For example, we can call the teacher and record it quietly during the call. Keep calm in the conversation, don't rush for success, and slowly guide the teacher to tell the key information. After the call, we need to back up the recorded content to the computer and mobile phone in case it is lost.
Upload evidence
If the above measures have no effect, you can consider uploading the evidence online and spreading it through social media and other platforms. This will let more people know the truth of the matter and urge relevant departments to solve the problem through public opinion.