Ultimately children who challenge us at home or at school are our greatest teachers--they teach us about situations in life that we don't know about. These challenging children can try our souls too because they demand our attention, time, flexibility, deep think, and change--they don't fit the status quo, they are change agents.
In my own family each of my children have been challenging from one time to another. I have struggled with their decisions, outlook, needs, and challenges, and I have been left with the question, "What do I do now?"
With my own children, I generally seek consult online or in real time by finding those who have dealt with similar issues and hearing what they have to say. It's the same at school. When children present new and challenging situations, I have to reach out to others and research to understand the situation to determine what I need to do. That doesn't mean I don't get frustrated in the meantime or try to ignore situations hoping that they'll go away, but in the long run, what I need to do is find out how to deal with the situation.
As a teacher one thing I've learned is that when a child begins to act out and demonstrate challenge early on, you have to pay attention. These kinds of actions almost never disappear, but instead become deeper and more troubling in time. Hence, it's best to pay attention right away and think about what the child needs and why the child is presenting the way he or she is presenting.
In general when children are getting the care, attention, and basic needs they need, they do well. It's typically when a child is missing something he/she needs that he/she acts out. That's when it is our job as educators to find out what that child needs to make things better and to meet that child's needs and challenges. This is challenging work whether you are a parent or a teacher, but it's a critical part of the teaching/learning role.