A、The book was written by David Baker. B、We can find information on about 15 countries in the book. C、The professors started to

A new book by two professors at Pennsylvania State University compares public education systems around the world. The book is called National Differences, Global Similarities: World Culture and the Future of Schooling.
    David Baker and Gerald LeTendre led a group of researchers who gathered information on about 50 countries. Some findings came from the Third International Mathematics and Science Study. That study took place in 1994 and again five years later.
    The professors say education is increasingly shaped by what they call “transnational forces”. Officials in many counties are concerned about how their students compare with students in other countries.
    Each part of the book develops a different subject researched in schools around the world. One of the subjects is violence among students. The professors say countries with the most school violence include Hungary, Romania and the Philippines.
    They say the United States is somewhere in the middle, above nations like New Zealand, Canada, South Korea, Spain and Australia. The findings are based on reports from students.
    Professor Baker says inequalities in educational systems act as an influence. He says schools that are sharply divided between “winners and losers” in math have higher levels of violence. “This does not mean that nations should stop trying to raise scores,” he says. “But they should be careful to raise the performance among all students.”