Among the 34 countries participating in testing students in reading, science and math, the United States ranked 26th in math, an assessment indicated. The 2012 Program for International Student Assessment ranking for the United States was comparable with Hungary, Italy, Lithuania, Norway, Portugal, the Russian Federation, the Slovak Republic, Spain and Sweden, the Organization for Economic Cooperation and Development said Tuesday in its report issued from France. The PISA report is the fifth triennial international survey that seeks to evaluate education systems worldwide by testing the skills and knowledge of 15- and 16-year-old students. OCED, which oversees the testing, said about 510,000 students participated in the latest assessment, representing about 28 million globally. The 26th-place ranking for the United States was below the average for math skills. The United States ranked 17 in reading and 21 in science, both near the testing average. OECD said the rankings reflected no significant change in these areas over the years PISA testing has taken place. Slightly more than one in four U.S. students hasn't reached the PISA baseline Level 2 of mathematics proficiency, higher than the average. The United States also has a below-average share of top math performers. Mathematics scores for the top-performer, Shanghai, China, indicate a performance that is the equivalent of more two years of formal schooling ahead of those in Massachusetts, a strong-performing U.S. state, results indicated. U.S. students are weak in performing mathematics tasks with higher cognitive demands, such as taking real-world situations, translating them into mathematical terms, and interpreting mathematical aspects in real-world problems, OECD said. The report said an alignment study between the Common Core State Standards for Mathematics and PISA suggests successfully implementing Common Core Standards would yield performance gains in PISA testing. In reading, the United States performed around the average, comparable with Austria, the Czech Republic, Denmark, France, Hungary, Israel, Italy, Norway, Portugal, Britain and Vietnam, the results indicated. Performance by U.S. students in science also was close to the OECD average, comparable with Austria, Belgium, Croatia, Denmark, France, Hungary, Italy, Latvia, Lithuania, Luxembourg, Norway, Portugal and Spain. The report said a student's socio-economic background had significant impact on performance in the United States, accounting for about 15 percent of the variation in student performance. While the socio-economic background has lessened over time, OECD said disadvantaged students tend to show less engagement, drive, motivation and self-beliefs. While U.S. students said they were largely satisfied with their school and teacher-student relations, they said they aren't strongly motivated to learn math, the report said. About 50 percent of the students said they were interested in learning mathematics, slightly below the OECD average of 53 percent.