The Organization for Economic Cooperation and Development (OECD) conducts a comparative study of the quality of secondary education in public schools around the world, noting the dynamics of indicators. Such monitoring has been organized and conducted by OECD since 2000 and is called PISA (Program for International Student Assessment). When assessing the results it is not so much the amount of mastered theoretical knowledge from the school program, but rather the ability to apply in practice in real life the knowledge obtained at school. Today, this is the most significant and objective indicator of the quality of secondary education in different countries. The survey is conducted every three years. Each time there are more and more countries participating in this study: so, in 2000 only 32 countries participated in the study, and in 2015 there are already 72.

According to the results of the PISA test in 2015, the U.S. took 31 place in the world in the overall ranking of countries by the level of preparedness of students, leaving behind Asian students (Singapore, Hong Kong, Japan, Macau, Taiwan, South Korea, China, Vietnam), Canadian, European (Estonia, Finland, Ireland, Slovenia, Germany, Holland, Switzerland, Denmark, Poland, Norway, Belgium, Great Britain, Portugal, France, Sweden, Austria, Spain, Russia and the Czech Republic), as well as students from New Zealand and Australia. The ranking was compiled by Medelle experts on the basis of PISA test data. The ranking is based on the points received by each country in the test (the higher the score, the higher position in the ranking). The final overall ranking is calculated as an arithmetic average of the scores in all 3 areas of knowledge.

Students in the United States scored just above the OECD average in Reading and Science, ranking well below average in Mathematics:

• 24th out of 70 in Reading (critical thinking)
• 25th out of 70 worldwide in Science
• 39th out of 70 in the world in Mathematics

The U.S. education system is also characterized by overall student achievement, clearly shown in the 2015 PISA study:

• 32nd in the world in the percentage of students who receive the highest grade in at least one area of study
• 32nd in the world in the percentage of students failing in all three areas