What strategies might teachers use to take a proactive approach in the classroom even if they do not know a student's trauma history?

First , teacher should expect any type of response from a student. It could be aggression, withdrawal, absenteeism etc. From experience a teacher should know students are different and they express themselves differently. Therefore, even if a student decides to remain mute in class, the teacher is not shocked.

The teacher should also focus on communication, activities and interactions that build relationships. The relationships will then be used to unravel the story

Third the teacher should inculcate predictability and consistency. This way, the teacher or other concerned people will know when the student is normal or abnormal.

Lastly, the teacher should teach positivity.. However, this is not easy because one doesn't know the trauma history. However, positive things are the same to everyone and  they are known by everyone E.g.. A teacher can always use words such as "You will get a better grade next term" to a student who doesn't pass. This positivity will make the learner change their thinking, meaning they stop focusing on the negative.

Step-by-step explanation

The above strategies focus on inculcating positivity in students.