It's a popular movie theme—the story of that one teacher who really connects with students, setting them on the right path to a productive future.

Now, thanks to a fascinating little experiment by Jason A. Okonofua and his colleagues at Stanford University, we know a little more about how schools could easily reduce discipline problems: make the teachers more empathetic.

Here's the setup. Math teachers in five California middle schools participated in just two short online sessions—one just 45 minutes long, the other a mere 25 minutes long. In these sessions they read stories about the importance of developing positive relationships with students. Then, they were asked to write about applying such approaches in their own teaching.

The brief, simple nature of this intervention makes the subsequent results all the more impressive. Compared to a control group, students taught by a "trained" teacher were half as likely to be suspended over the school year. Better still, this reduction held among students who had been previously suspended and for all race and gender subgroups. Previously suspended students clearly noticed the difference, reporting that their teachers treated them with more respect.

What made such a simple approach so powerful? It could be that it empowered teachers as experts. Initially, the researchers told the teachers that they were seeking their input as professional educators, noting that their writing exercise would become part of a new teacher training program, "so future teachers can benefit from your experience and insights." This approach encouraged teachers to see themselves as leaders rather than "recipients of remediation." Take note, PD providers.