Final answer:
Teachers should be aware of legal agreements regarding custody, the child's living arrangements, and what the child has been told about the situation in situations involving divorce.
Step-by-step explanation:
One thing teachers should know in situations involving divorce is that they should be aware of the legal agreements regarding custody (option A). They should also be aware of the child's living arrangements (option B) and what the child has been told about the situation (option C). The specific details of who filed for the divorce (option D) may not be as relevant as the other aspects mentioned.