Schools are not just four walls inside of which students learn how to read, write and think. Schools provide a venue where young people meet each other, and where they develop relationships and friendships that may last for decades. At school, students socialise and hone the interpersonal skills that are required to function effectively in the workplace and in society at large. Employers value such skills more now than ever before: wages have risen more for jobs that demand a high level of social skills than for jobs that require only a low level of social skills. But until now, there was no measure of students' ability to work together that was consistent across countries. PISA changed that when it introduced its collaborative problem-solving assessment in 2015, which, more specifically, measured students' ability to work together to solve problems and achieve goals.