Exhibits 9.9, 9.10, 9.11, and 9.12 present teachers’ reports about their years of teaching experience, including the average years of experience in each country and the percentage of students and average achievement by four categories: 20 years or more, at least 10 but less than 20 years, at least 5 but less than 10 years, and less than 5 years.

There was considerable variation in teacher experience across countries in both grades and subjects. In some countries, two-thirds or more of the students were taught by very experienced teachers with more than 20 years of experience, while in others, about a quarter of students were taught by teachers with less than 5 years of experience.

On average across countries, fourth grade students’ mathematics and science teachers had been teaching for 17 years. In mathematics, experience ranged from an average of 9 years in Turkey and 10 years in England to more than 25 years in Bulgaria (26 years), Latvia and Lithuania (27 years), and the Russian Federation (26 years). In science, experience ranged from 10 years in England and Pakistan to 25 years or more in Bulgaria, Hungary, and Latvia (25 years); the Russian Federation (26 years); and Lithuania (27 years). On average across countries, just over 40 percent of fourth grade students were taught by teachers with 20 years of experience (41% for mathematics and 40% for science); 29 and 28 percent by mathematics and science teachers, respectively, with at least 10 but less than 20 years; 15 percent by mathematics teachers and 17 percent by science teachers with at least 5 but less than 10 years of experience; and 14 percent by mathematics teachers and 15 percent by science teachers with less than 5 years of experience.

On average, eighth grade teachers were slightly less experienced than their fourth grade counterparts (16 years of experience for both subjects, compared with 17 years in fourth grade). In mathematics, experience ranged from an average of 10 years in Turkey to 29 years in Lithuania. In science, teachers’ average years of experience ranged from 11 years in Jordan, Lebanon, and Qatar to 26 years in Georgia and Lithuania. In both subjects, just over one-third of eighth grade students had teachers with more than 20 years of experience (35% in mathematics and 34% in science); about one-third had at least 10 but less than 20 years of experience (33% in mathematics and 32% in science); 18 percent had teachers with at least 5 but less than 10 years; and 14 percent (mathematics) and 15 percent (science) had teachers with less than 5 years of experience. Internationally, average mathematics and average science achievement were generally higher for students whose teachers had more experience. For example, in mathematics in fourth grade, average achievement rose from 494 among students of teachers with less than 5 years of experience to 500 to 504 for the other categories. Similarly, in science in fourth grade, the average achievement was 485 for the lowest category of experience and rose to 492 for each of the other three categories. The relationship between experience and average student achievement was also more pronounced in mathematics than in science, in both grades.

Policies for teacher assignment may play a role in the relationship between teacher experience and average student achievement, as sometimes, more experienced teachers are assigned to students of higher ability and with fewer discipline problems and, conversely, less experienced teachers are assigned to students of lower ability.