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 fifty countries. Some findings came from the Third International Mathematics and Science Study. That study took place in nineteen ninety-four and again five years later.

The professors say education is increasingly shaped by what they call "transnational forces." Officials in many countries 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."

Also, the researchers often found no connection between national performance and the average amount of homework given in a nation. Teachers generally give little homework in countries with the highest average test scores, such as Japan, the Czech Republic and Denmark. But the professors say teachers in countries with low average test scores like Thailand, Greece and Iran often give lots of homework.

Yet the authors say most teachers worldwide could learn to make better use of homework. Children are mostly given material to remember. But conditions at home, especially in poorer families, may not support the kind of environment needed to do such work.

This VOA Special English Education Report was written by Nancy Steinbach. Our reports are on the Web at WWW.51VOA.COM. I'm Gwen Outen.