andreas schleicher serves as deputy director for education and skills there.helped develop and runs the tests, and joins us now. >> so explain to us first, what is the role and importance of these tests? what do they actually tell us? >> well, they allow us to look at what is possible in education. they show us what the world's leading education systems, what is possible in terms of student achievement, in terms of equity in educational opportunities, they are very important in which we can look at ourselves in the light of what other countries show is possible, really. >> so when we look at ourselves, the headline once again was, average. is that the -- >> some countries have moved ahead. is that the take away that you would put for the u.s.? >> well, yes, i think the u.s. is an average performer. will is a lot of movement around the world, change high, singapore moving from good to great, in europe, poland, germany actually addressing many of the same challenges the u.s. faces in terms of creating more equitable distribution of learning opportunities, and a