We have struggled a lot to write this article because we were too worried about technicalities. But, then, it occurred to us that social and emotional learning (SEL) competencies are anything but technical. And that is exactly why we need them right now. In Brazil, with our crowded classrooms, we have never really given personalized learning a try, at least not outside elite schools. Everything comes to numbers in the end. This is how we define who goes to college. And this is how we decide whether a school...