Exhibits 9.1, 9.2, 9.3, and 9.4 present teachers’ reports about their highest level of formal education for fourth grade mathematics and science teachers and eighth grade mathematics and science teachers, respectively. Teachers’ highest levels of formal education are reported by four categories: completed postgraduate university degree, completed a bachelor’s degree or equivalent, completed post-secondary education but not a bachelor’s degree, or completed upper-secondary education.

Internationally, on average, 28 percent of the fourth grade students had mathematics teachers with a postgraduate university degree, 56 percent had teachers with a bachelor’s degree, 10 percent had teachers who had completed post-secondary education, and 5 percent had teachers who completed upper-secondary education (Exhibit 9.1). Similarly, on average, 29 percent of fourth grade students had science teachers with a postgraduate university degree, 56 percent had teachers with a bachelor’s degree, 10 percent had teachers with some post-secondary education, and 5 percent had teachers who completed upper-secondary education (Exhibit 9.2).

Parallel results are shown for eighth grade students in Exhibit 9.3 (mathematics) and Exhibit 9.4 (science), although in both subjects, more eighth grade students than fourth grade students had teachers with bachelor’s degrees and postgraduate university degrees, on average. Internationally, 35 percent of students had mathematics teachers with a postgraduate university degree, and 61 percent had mathematics teachers with a bachelor’s degree. Also internationally, 38 percent of students had science teachers with a postgraduate university degree, and 58 percent had science teachers with a bachelor’s degree.

In fourth and eighth grades and in both subjects, there was considerable variation across countries in teachers’ education levels, reflecting countries’ different education paths and requirements for teachers. The TIMSS 2019 Encyclopedia provides information about the main teacher preparation routes and current requirements for teachers in each country, based on information provided by National Research Coordinators in the TIMSS 2019 Curriculum Questionnaire.

Exhibits 9.5 and 9.6 present fourth grade teachers’ reports about their majors or specializations in primary education and/or mathematics and in primary education and/or science, respectively. Exhibits 9.7 and 9.8 present eighth grade teachers’ reports about their majors or specializations in mathematics and/or mathematics education and in science and/or science education, respectively. For each category of teachers’ major or specialization, average student achievement is also shown.

As shown in Exhibit 9.5, on average across countries, three-quarters of fourth grade students were taught by teachers with a major in primary education and a major or specialization in mathematics (32%) or by teachers with a major in primary education but no major or specialization in mathematics (43%), and just 11 percent were taught by teachers with a major in mathematics but not primary education. Another 8 percent were taught by teachers who had some other major, and 6 percent by teachers with no formal education beyond upper-secondary. The distribution of students by teachers’ major was similar for science (shown in Exhibit 9.6), with 28 percent of fourth grade students taught by science teachers with a major in primary education and science, 44 percent by teachers with a major in primary education but not in science, 13 percent by teachers with a major in science but not primary education, and 9 and 5 percent by teachers with other majors or no education beyond upper-secondary, respectively. In both mathematics and science, there was considerable variation in the distribution of students by teachers’ majors across countries, however, reflecting countries’ different education pathways and requirements for primary school teachers.

On average across countries, mathematics achievement was highest for fourth grade students whose teachers had a major in primary education but no major in mathematics (503), followed by students with teachers with a major in both primary education and mathematics (497), and then by students with teachers who majored in mathematics but not primary education (487) and teachers who had other majors (490). Students whose teachers did not go beyond upper-secondary education had the lowest average mathematics achievement (457). Likewise, for science, students who had teachers with a major in primary education but no major in science and students who had teachers with a major in primary education and science had the highest average achievement (491 and 489, respectively), followed by students whose teachers majored in science but not primary education (480), and then by students who had teachers with other majors (478). Students whose teachers had no formal education beyond upper-secondary had the lowest average science achievement (442). However, within most countries, there was no clear relationship between teachers’ major and average achievement in mathematics and science.

As shown in Exhibit 9.7, about three-quarters (78%) of eighth grade students were taught mathematics by teachers who had a major in mathematics and mathematics education (39%) or who majored in mathematics but not in mathematics education (39%). A further 11 percent were taught by teachers who majored in mathematics education only, and 10 percent by teachers with other majors. A slightly higher percentage (83%) of eighth grade students were taught science by teachers who majored in science and science education (33%) or in science but not in science education (50%), as shown in Exhibit 9.8. A further 9 percent were taught by teachers who majored in science education but not science and 6 percent by teachers with other majors. Internationally, just 1 percent of eighth grade students were taught mathematics or science by teachers who had not completed formal education beyond upper-secondary.

In mathematics, eighth grade students with teachers who majored in mathematics and mathematics education or in mathematics education but not mathematics had higher average achievement than students with teachers who majored in mathematics and not mathematics education (averages scores of 492 and 494 compared with 488, respectively). That was not the case in all countries, however, and in many countries, there was no clear relationship between teachers’ major and average mathematics achievement. In science, eighth grade students whose teachers majored in science and science education or in science but not science education had higher average scores than students whose teachers majored in science education but not science (494 and 491 compared with 482, respectively). However, within most countries, there was no clear relationship between teachers’ major and average achievement science.

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.

Exhibits 9.13, 9.14, 9.15, and 9.16 present, for fourth grade mathematics and science and eighth grade mathematics and science, respectively, teachers’ reports about their participation in professional development during the last two years. Mathematics teachers in both grades were asked whether they had participated in professional development in the following areas: mathematics content, mathematics pedagogy/instruction, mathematics curriculum, integrating technology into mathematics instruction, improving students’ critical thinking or problem solving skills, mathematics assessment, and addressing individual students’ needs. Science teachers in both grades were asked about the same areas, though specific to science instead of mathematics, including asking about professional development related to students’ critical thinking and inquiry skills rather than problem solving skills. Teachers of fourth grade science were also asked about professional development related to integrating science with other subjects.

Although there was variation across countries, the most common areas of mathematics professional development for mathematics teachers of fourth grade students on average were mathematics content, mathematics pedagogy/instruction, and improving students’ critical thinking or problem solving skills. As shown in Exhibit 9.13, on average across countries, between 44 and 46 percent of fourth grade students’ teachers participated in professional development related to mathematics content (46%), mathematics pedagogy/instruction (45%), and improving students’ critical thinking or problem solving skills (44%). Integrating technology into mathematics instruction and mathematics assessment were the least common areas, with teachers of 35 percent and 37 percent of students, respectively, reporting that they participated in professional development in these areas. In science in the fourth grade, improving students’ critical thinking or inquiry skills in science, science content, and science curriculum were the three most common areas of professional development. However, participation in professional development related to science was on the whole less common than for mathematics in the fourth grade. As shown in Exhibit 9.14, just over one-third of students, on average, had science teachers who reported that they participated in professional development related to critical thinking or inquiry skills in science (36%), science content (35%), and science curriculum (34%). Integrating technology into the science curriculum and science assessment were two of the least common areas for professional development (32% and 28% of students, respectively), along with integrating science with other subjects (31% of students).

Teachers of eighth grade students reported somewhat higher levels of participation in professional development than teachers of fourth grade students. Eighth grade teachers of mathematics and science reported similar levels of participation. As shown in Exhibits 9.15 and 9.16, the three most common areas of professional development for both teachers of mathematics and science were pedagogy/instruction, content, and curriculum. More than 50 percent of students, on average, had teachers who reported that they participated in professional development related to pedagogy/instruction (60% in mathematics and 59% in science), content (57% in both), and curriculum (53% in mathematics and 52% in science). From 44 percent to 50 percent of eighth grade students were taught by teachers who had some professional development in the other four areas, with addressing individual students’ needs being the least common area (44% of students for both subjects).

Along with being asked about participation in professional development in the last two years (Exhibits 9.13 through 9.16), teachers were asked about their need for future professional development in the same areas. Teachers’ reports on their professional development needs are presented in Exhibits 9.17, 9.18, 9.19, and 9.20, for fourth grade mathematics and science and eighth grade mathematics and science, respectively.

On average across countries, professional development related to integrating technology into instruction and improving students’ critical thinking skills were the two areas of need most commonly reported by mathematics and science teachers in the fourth and eighth grades. In both grades and both subjects, 68 to 72 percent of students had teachers who identified integrating technology into instruction as a need (72% in fourth grade mathematics, 68% in fourth grade science, 71% in eighth grade mathematics, and 70% in eighth grade science); 65 to 69 percent of students had teachers who identified improving critical thinking or problem solving/inquiry skills as a need (69% in fourth and eighth grade mathematics, 65% in fourth grade science, and 68% in eighth grade science). Addressing individual students’ needs was the third most commonly reported area of need for teachers of mathematics in both grades and teachers of science in eighth grade; 64 to 66 percent of students had teachers who identified addressing individual students’ needs as a professional development need (64% for fourth grade mathematics, 65% for eighth grade mathematics, and 66% for eighth grade science). In fourth grade science, the third area of greatest need was integrating science into other subjects (62%).

It is perhaps not surprising that integrating technology into instruction was a common need given the growing role of technology in instruction and, in fourth grade, it was one of the less common areas of teachers’ reported participation. Addressing individual students’ needs was also one of the less commonly reported areas of professional development participation for eighth grade mathematics teachers and science teachers in both grades (see Exhibits 9.13 through 9.16).

Teachers who are satisfied with their profession are more motivated, may be more likely to continue teaching into the future, and may experience greater overall well-being. The TIMSS 2019 Teachers’ Job Satisfaction scale, based on teachers’ responses to five statements about how they feel about being a teacher, is described in Exhibit 9.21 (see About the Scale). Exhibits 9.22, 9.23, 9.24, and 9.25 present teachers’ reports of their job satisfaction, including the percentage and average achievement of students with teachers who reported they were “very satisfied,” “somewhat satisfied,” and “less than satisfied,” and the average scale score on the Teachers’ Job Satisfaction scale, for each country. Countries are ordered by the percent “very satisfied.”

Across the TIMSS 2019 countries, almost all students in fourth and eighth grades were taught mathematics and science by teachers who were “very satisfied” or “somewhat satisfied” with being a teacher, with job satisfaction somewhat higher among fourth grade teachers than eighth grade teachers. In fourth grade, 61 percent of students were taught mathematics and science by teachers who reported they were “very satisfied,” and 34 percent were taught by teachers who reported they were “somewhat satisfied.” Only 5 percent of students had mathematics or science teachers who reported they were “less than satisfied.” In eighth grade, 54 percent of students had mathematics teachers and 53 percent of students had science teachers who said they were “very satisfied,” 39 percent of students had mathematics and science teachers who said they were “somewhat satisfied,” and 7 and 8 percent of students had mathematics and science teachers, respectively, who reported they were “less than satisfied.”

In fourth grade, average achievement was somewhat higher for students of “very satisfied” teachers compared with “somewhat satisfied” teachers (503 vs. 499 in mathematics and 493 vs. 490 in science). Counterintuitively, in both subjects, average achievement was highest for students with “less than satisfied” teachers (515 for mathematics and 508 for science), though there were few students in this category, and in some countries, there were so few that average achievement could not be estimated. In the eighth grade, average achievement was also higher for students with “very satisfied” compared with “somewhat satisfied” teachers (493 vs. 486 for mathematics and 494 vs. 486 for science). In both subjects, for the few students with “less than satisfied” teachers, average achievement was close to that of students with “somewhat satisfied” teachers (490 in mathematics and 488 in science).

Exhibits 10.1, 10.2, 10.3, and 10.4 present students’ reports about the frequency they are absent from school—“never or almost never,” “once every two months,” “once a month,” “once every two weeks,” and “once a week,” with the percentage of students and average achievement reported for each category. Countries are sorted by the percentage of students reporting they are “never or almost never” absent.

In fourth grade (Exhibits 10.1 and 10.2), 61 percent of students, on average, reported they are “never or almost never” absent, 13 percent that they are absent “once every two months,” 10 percent that they are absent “once a month,” 5 percent that they are absent “once every two weeks,” and 11 percent that they are absent “once a week.” Just over half (55%) of eighth grade students said they are absent “never or almost never,” 16 percent that they are absent “once every two months,” 14 percent “once a month,” 7 percent “once every two weeks,” and 8 percent “once a week” (Exhibits 10.3 and 10.4). In both grades, students in Korea reported the lowest rate of absenteeism, with 88 percent of fourth grade students and 94 percent of eighth grade students reporting that they are “never or almost never” absent, and just 1 percent or less saying that they are absent “once a week.” In contrast, in some countries, more than one-fifth or more of students miss school “once a week.”

Because coming to school is the foundation for having an opportunity to learn, it is not surprising that an increase in frequency of being absent is highly related to a decrease in average achievement, especially for students absent “once every two weeks” or more. For example, the average mathematics score in eighth grade decreased from 502 for students “never or almost never” absent to 495 for students absent “once every two months,” to 475 for students absent “once a month,” to 452 for students absent “once every two weeks,” and to 412 for students absent “once a week”—a 90-point difference between regular attendance and missing school very often. Frequently missing school may indicate that a student has other challenges, which can cause or compound the problem of missed instruction.

Exhibits 10.5, 10.6, 10.7, and 10.8 contain students’ reports about the frequency with which they arrive at school feeling tired or hungry, along with average achievement by frequency. Lack of adequate sleep or nutrition can have serious implications for a student’s ability to focus on learning and also may be indicative of other challenges that students face.

On average across countries, just over one-third (35%) of fourth grade students and 45 percent of eighth grade students reported that they arrive at school feeling tired “every day or almost every day.” Only 19 percent of fourth grade students and 8 percent of eighth grade students reported “never” arriving at school feeling tired, and nearly half (47%) of students in both grades reported “sometimes” arriving feeling tired. On average, achievement was lowest for fourth grade students who reported feeling tired “every day or almost every day,” though it was highest for students “sometimes” arriving at school feeling tired compared with “never” doing so. In eighth grade, average mathematics achievement was 488 for “never” arriving at school feeling tired and 487 for doing so “every day or almost every day,” while it was 493 for “sometimes” arriving at school feeling tired (Exhibit 10.7). Average science achievement was lowest for the 8 percent of eighth grade students reporting they “never” arrived at school feeling tired (Exhibit 10.8).

More than one-quarter (28%) of fourth grade students reported that they arrived at school hungry “every day or almost every day,” and 41 percent said they “sometimes” did. Just under one-third (31%) reported that they “never” arrived at school hungry. Frequent hunger was a somewhat bigger problem in eighth grade, with 33 percent of students reporting that they arrived at school hungry “every day or almost every day” and another 42 percent of reporting that they did so “sometimes.” Only 25 percent said they “never” arrived at school hungry. There was a direct relationship between the frequency of arriving at school hungry and average achievement in both grades and subjects. For example, in fourth grade science (Exhibit 10.6), students arriving at school hungry “every day or almost day” had an average score of 478, compared with 497 for students who did so “sometimes” and 504 for students who “never” did.

Exhibits 10.10, 10.11, 10.12, and 10.13 present teachers’ reports about the extent to which their fourth and eighth grade classroom teaching is limited by students not ready to learn (i.e., lacking prerequisite knowledge or skills, lacking basic nutrition, being sleep deprived, absent, disruptive, or uninterested, or having learning impairments or difficulties understanding the language of instruction), along with student achievement. The results are summarized on the Classroom Teaching Limited by Students Not Ready for Instruction scale described in Exhibit 10.9 (see About the Scale), with three categories that describe how much classroom teaching is limited: “very little,” “some,” and “a lot.” A higher score on the scale indicates that classroom instruction was limited less by these student attributes or behavior, and a lower score indicates it was limited more. Countries are sorted by the percentage “very little.”

On average, across countries, just over one-third of the fourth grade students (36% for mathematics and 37% for science) had classroom teachers who reported that their teaching was limited “very little” by students not ready for instruction. Most of the rest of the students (59% in mathematics and 58% in science) had teachers who reported that instruction was limited “some.” Unfortunately, 6 percent of students were in classrooms where teachers reported instruction was limited “a lot.” The picture was even less positive in eighth grade, where only about one-quarter of students (24% in mathematics and 26% in science) had teachers who reported that classroom instruction was limited “very little,” and about two-thirds (67% for mathematics and 66% for science) had teachers who reported that classroom instruction was limited “some” by students not ready for instruction. The remaining 8–9 percent of students (9% in mathematics and 8% in science) had teachers reporting instruction was limited “a lot.”

In both subjects and both grades, there was a direct relationship between the degree that instruction was limited by students not ready for instruction and students’ average achievement, with successively lower achievement for each category of increased impact on teaching. For example, in eighth grade science (Exhibit 10.13), average achievement was 515 for students where instruction was limited “very little,” 484 for students where instruction was limited “some,” and 457 for students where instruction was limited “a lot.”

Exhibit 11.1 presents the Students Like Learning Mathematics scale administered to fourth and eighth grade students. In TIMSS 2019, the scale had nine items covering students’ attitudes toward mathematics and studying mathematics (see Mathematics—About the Scale). In each TIMSS cycle since 1995, there has been a positive relationship between students liking mathematics and higher mathematics achievement. Since the inception of an item response theory (IRT) scale in 2011 to measure attitudes more broadly and reliably, the Students Like Learning Mathematics scale has had a very strong relationship with achievement in mathematics, and TIMSS 2019 was no exception. At both fourth and eighth grades, students who reported they “very much” like learning mathematics had substantially higher average achievement than students who reported they “do not like” learning mathematics.

Exhibit 11.2 presents the results for fourth grade according to the percentage of students who reported they like to learn mathematics “very much” (from highest to lowest). In general, fourth grade students were positive about learning mathematics—45 percent, on average, responded they like it “very much,” and another 35 percent reported that they “somewhat” like it. However, even at the fourth grade, 20 percent, on average, responded negatively that they “do not like” learning mathematics. Exhibit 11.3 shows that at the eighth grade, the percentage of students responding negatively increased substantially. At the eighth grade, only 20 percent responded that they like learning mathematics “very much.” Thirty-nine percent responded “somewhat,” and 41 percent (double compared with fourth grade) responded that they “do not like” learning mathematics. The difference in average achievement between eighth grade students who like learning mathematics “very much” and those who “do not like” learning mathematics was 62 scale score points.

Exhibit 11.4 presents the Students Like Learning Science scale (parallel to the mathematics scale) which was administered to fourth and eighth grade students (see Science—About the Scale). At both grades, the Students Like Learning Science scale was related to higher average achievement in science.

Exhibit 11.5 shows the science scale results at fourth grade. Compared with mathematics, a greater percentage of fourth grade students were positive about learning science, with 52 percent responding that they like it “very much,” and another 36 percent that they “somewhat” like it. A smaller percentage were negative about learning science—12 percent reported they “do not like” it.

Exhibit 11.6 contains the eighth grade results for the Students Like Learning Science scale. The first panel is for the 26 countries that taught science as an integrated subject, then there are separate panels for the countries with courses for biology, chemistry, physics, and Earth science. The eighth grade students generally were positive about their integrated science courses, with 35 percent of students responding that they like to learn science “very much,” another 44 percent liking it “somewhat,” and only 20 percent of students in the “do not like” category. Similar to the relationship with mathematics achievement, the difference in average science achievement between eighth grade students who like learning science “very much” and those who “do not like” learning science was 64 scale score points.

In countries where science is taught as separate subjects, students were positive about learning biology, with only 22 percent of students in the “do not like” learning biology category. Students were less positive about their separate courses in chemistry, physics, and Earth science, with 28 percent, 31 percent, and 26 percent of students in the “do not like” category of the three respective subjects, but not as negative as they were about eighth grade mathematics. The difference in average achievement between eighth grade students in the “very much like” and “do not like” categories was smaller for students taking separate subject courses and varied across the four subjects—30 points for biology, 45 points for chemistry, 46 points for physics, and 22 points for Earth science.

Exhibit 11.7 presents the Students Confident in Mathematics scale, which contains nine statements about how well students think they can do mathematics (see Mathematics—About the Scale). Both fourth grade and eighth grade students responded to the scale and appear to have a good idea about their relative abilities. At both grades, students expressing confidence had substantially higher average achievement than those not expressing confidence.

Exhibit 11.8 presents the fourth grade results for the Students Confident in Mathematics scale. Thirty-two percent of the fourth grade students reported being “very confident,” 44 percent “somewhat confident,” and 23 percent “not confident.” Exhibit 11.9 presents the eighth grade results. At the eighth grade, students’ confidence had eroded, with only 15 percent reporting they are “very confident,” 42 percent “somewhat confident,” and 44 percent “not confident.” The gap in average achievement between the “very confident” and “not confident” eighth grade students was more than 100 scale score points (562 vs. 456).

Exhibit 11.10 contains the corresponding confidence scale for science (see Science—About the Scale). Both fourth and eighth grade students responded, with the results at the fourth grade being similar to but slightly more positive than those in mathematics. As shown in Exhibit 11.11, 38 percent of the fourth grade students reported being “very confident,” 43 percent “somewhat confident,” and 19 percent “not confident.”

Exhibit 11.12 presents the eighth grade results for the Students Confident in Science scale. The first panel shows the results for countries that have science as an integrated subject, followed by the results for biology, chemistry, physics, and Earth science as separate courses. Eighth grade students did not report being as confident in doing science as did fourth grade students. However, relatively speaking, the eighth grade students expressed the most confidence in biology and Earth science, with 22–23 percent “very confident,” 46 percent “somewhat confident,” and 31–32 percent “not confident.” Although less positive, the results also were similar for integrated science and chemistry—20–23 percent “very confident,” 39 percent “somewhat confident,” and 38–41 percent “not confident.” Eighth grade students’ confidence in physics was the lowest of the science results (and similar to mathematics). Only 17 percent reported “very confident,” 38 percent “somewhat confident,” and 44 percent “not confident.”

Exhibits 11.13 and 11.15 present the two parallel scales: Students Value Mathematics and Students Value Science, respectively (see About the Scale). The TIMSS 2019 context questionnaire framework cites research showing that if students understand the value of learning these subjects, it may ameliorate some of their other negative attitudes.

Exhibit 11.14 shows that eighth grade students generally value mathematics. Thirty-seven percent responded that they “strongly value” mathematics, 47 percent responded “somewhat value,” and only 16 percent responded “do not value.” The results were similar, but slightly less positive for science, shown in Exhibit 11.16—36 percent “strongly value,” 42 percent “somewhat value,” and 22 percent “do not value” science. There was a strong positive relationship between valuing mathematics and science and average achievement in each of the respective curriculum areas. However, the relationship between higher achievement and valuing the subjects was less pronounced than between higher achievement and attitudes toward liking the subjects or having confidence in your ability to do well in the subjects.

Though many factors influence the relationship between amount of instructional time and student achievement—primarily, the quality of the instruction and the students’ readiness to learn—instructional time remains a crucial component in considering students’ opportunity to learn. Instructional time was calculated using principals’ reports on the number of school days per year and the number of instructional hours per day and teachers’ reports on the weekly number of hours of mathematics instruction, as explained in Exhibit 12.1 (see About the Scale). Exhibits 12.2 and 12.3 present principals’ and teachers’ reports about the instructional hours per year overall spent on mathematics instruction in fourth grade and eighth grade, respectively. Countries are ordered by the number of hours per year for mathematics instruction.

On average, the fourth grade students across the TIMSS 2019 countries received 895 hours per year of instruction across all subjects, and 154 hours, or about 17 percent of the total, were devoted to mathematics instruction. The number of hours devoted to mathematics instruction ranged from a high of 250 hours in Portugal to 101 in Korea. The amount of mathematics instructional time relative to total instructional time varied considerably across countries, reflecting different approaches to organizing and addressing the mathematics curriculum. As might be anticipated, within-country estimates of instructional time can vary somewhat from the levels of instructional time established by policy (see TIMSS 2019 Encyclopedia).

The eighth grade students across the TIMSS 2019 countries received an average of 1,023 hours of instruction across all subjects, and 137 hours, or 13 percent of the total, were devoted to mathematics instruction. The number of hours for mathematics instruction ranged from 200 in Chile to 102 in Cyprus. Of the countries that participated in TIMSS at the fourth and eighth grades, in most countries, the number of annual hours devoted to mathematics instruction decreased between fourth and eighth grades, likely because by eighth grade, the school curriculum covers many more subjects than in fourth grade.

The mathematics content domains and underlying topic areas assessed in TIMSS 2019 are documented in the TIMSS 2019 Mathematics Framework, which was developed in collaboration with the participating countries. The mathematics topics included in the TIMSS assessments do not represent the intersection of the topics that are universally taught but rather are a forward-looking conception of mathematics teaching and learning.

Exhibit 12.4 shows the TIMSS mathematics content domains—number, measurement and geometry, and data—and the 17 underlying topics in the TIMSS fourth grade mathematics assessment (see About the Scale). There were 7 topics in number, 7 in measurement and geometry, and 3 in data. Exhibit 12.6 shows the same information for the eighth grade mathematics assessment, with its four content domains—number, algebra, geometry, and data and probability and the 22 underlying topics. There were 3 topics in number, 7 in algebra, 6 in geometry, and 6 in data and probability. Teachers were asked to indicate, for each topic, whether it had been “mostly taught before this year” to students in the assessed class or “mostly taught this year,” or had been “not taught or just introduced” to students. This information serves as an indicator of the “implemented curriculum.” It also can be examined together with information provided by TIMSS National Research Coordinators about whether each of the TIMSS 2019 mathematics topics was included in their countries’ intended curriculum through the fourth or eighth grade and, if so, whether the topics were intended to be taught to “all or almost all students” or “only the more able students.” This information about the intended curriculum is reported in the TIMSS 2019 Encyclopedia.

Exhibit 12.5 presents fourth grade teachers’ reports about the TIMSS mathematics topics that had been taught to students in fourth grade classrooms either prior to or during the year of the assessment. The exhibit shows, for each country and the international average, the percentage of students whose teachers reported that the students had been taught each of the topics (before or during the year), averaged across all topics in each mathematics content domain, and also across all topics in all mathematics domains. Exhibit 12.7 presents parallel information for the eighth grade, reported by teachers about the TIMSS mathematics topics in the eighth grade assessment.

In the fourth grade, according to their teachers, 80 percent of students, on average, had been taught the TIMSS mathematics topics overall. This finding ranged from 97 percent in Azerbaijan and Portugal to 62 percent in Morocco. On average, 86 percent of students had been taught the TIMSS number topics, and 76 percent and 78 percent had been taught the measurement and geometry and data topics, respectively. There was, however, considerable variation from content domain to content domain and from country to country, reflecting differing mathematics curricular emphases.

In the eighth grade, on average, 72 percent of students had been taught the TIMSS mathematics topics overall, according to their teachers. Teachers’ reports about the degree of implementation ranged from 95 percent of students in Malaysia to 49 percent in Finland. Almost all of the students (98%), on average, had been taught the number topics by the end of eighth grade, according to their teachers, with 100 percent of students in a number of countries. The coverage of algebra and geometry was lower, with 68 percent of the students having been taught the algebra topics and 76 percent having been taught the geometry topics, on average. The least instructional attention was given to the topics in data and probability, with 60 percent of students having been taught the topics in this domain, on average. There was considerable variation across countries, particularly in the percentages of students taught the data and probability topics.

The clarity with which teachers convey the curriculum to students has significant implications for student learning. Students were asked about aspects of teachers’ mathematics instruction during their mathematics lessons: whether they know what their teacher expects them to do, and whether their teacher is easy to understand, has clear answers to their questions, is good at explaining mathematics, does a variety of things to help the students learn, links new lessons to previous knowledge (eighth grade only), and explains a topic again when the students do not understand. Responses were combined into the TIMSS Instructional Clarity in Mathematics Lessons scale, as described in Exhibit 12.8 (see About the Scale). Exhibits 12.9 and 12.10 present students’ reports about the clarity of their mathematics lessons, for fourth grade and eighth grade, respectively. Countries are ordered by percentage reporting “high clarity of instruction.”

On average, about three-quarters (74%) of fourth grade students reported that their mathematics instruction had “high clarity,” 21 percent reported “moderate clarity,” and just 5 percent characterized their instruction as having “low clarity.” There was a range in views across countries with, interestingly, lower percentages of students characterizing their instruction as having “high clarity” in some of the higher performing countries, such as Korea and Japan. On average, internationally and within most countries, however, more clarity was associated with higher average achievement. Across countries, average achievement was 508 among students reporting that their instruction had “high clarity,” 488 among students reporting “moderate clarity,” and 466 among students reporting “low clarity,” a remarkable 42-point difference between “high clarity” and “low clarity.”

Eighth grade students were less positive about the clarity of their mathematics instruction, with less than half (46%) internationally reporting that their instruction had “high clarity,” 41 percent reporting “moderate clarity,” and 13 percent reporting “low clarity.” As in fourth grade, some of the higher performing countries had the lowest percentages of students reporting that their instruction had “high clarity,” including Korea, Japan, and Hong Kong SAR. Also as seen in fourth grade, clarity of instruction was positively associated with achievement. On average, students reporting “high clarity” of instruction had an average score of 504, followed by an average of 482 for “moderate clarity,” and 467 for those reporting “low clarity.”

Good classroom management and having students who pay attention and focus on the lessons help create a classroom environment conducive to student learning. Students were asked about the frequency of disorderly behavior during mathematics lessons, including whether students do not listen to what the teacher says, there is disruptive noise, it is too disorderly for students to work well, the teacher has to wait a long time for students to quiet down, students interrupt the teacher, and the teacher has to keep telling students to follow the classroom rules. These responses were combined into the Disorderly Behavior During Mathematics Lessons scale, described in Exhibit 12.11 (see About the Scale). Exhibits 12.12 and 12.13 present students’ reports about disorderly behavior for fourth and eighth grades, respectively. Countries are ordered by the percentage reporting disorderly behavior in “few or no lessons.”

In fourth and eighth grades, about two-third of students (68% in fourth grade and 65% in eighth grade) reported disorderly behavior in “some lessons,” on average, and about one-fifth (18% in fourth grade and 21% in eighth grade) reported it in “few or no lessons.” Fourteen percent of fourth grade students and 13 percent of eighth grade students reported disorderly behavior in “most lessons.” Internationally and in most countries, there was a clear negative association between the frequency of disorderly behavior and average student achievement, with average achievement decreasing with higher frequencies of disorderly behavior. For example, in eighth grade, students reporting disorderly behavior in “few or no lessons” had an average score of 502, followed by 485 for students reporting it in “some lessons,” and 466 for students reporting it in “most lessons.”

Though many factors influence the relationship between amount of instructional time and student achievement—primarily, the quality of the instruction and the students’ readiness to learn—instructional time remains a crucial component in considering students’ opportunity to learn. Instructional time was calculated using principals’ reports on the number of school days per year and the number of instructional hours per day and teachers’ reports on the weekly number of hours of science instruction, as explained in Exhibit 13.1 (see About the Scale). Exhibits 13.2 and 13.3 present principals’ and teachers’ reports about the instructional hours overall per year and hours spent on science instruction in fourth grade and eighth grade, respectively. For countries teaching science as separate subjects in the eighth grade, the instructional time included the amount of time spent on each individual science subject. Countries are ordered by the number of hours per year for science instruction.

On average, the fourth grade students across the TIMSS 2019 countries received 895 hours per year of instruction across all subjects; 73 hours, or about 8 percent of the total, were devoted to science instruction. The number of hours devoted to science instruction ranged from a high of 158 hours in the Philippines to just 34 hours in Ireland. The amount of science instructional time relative to total instructional time also varied across countries, reflecting different approaches to organizing and addressing the science curriculum. It is notable, though, that there is much less science instructional time for fourth grade students across countries compared with mathematics. As shown in Exhibit 12.2, fourth grade students had an average of 154 hours of mathematics instruction, more than twice that for science (Exhibit 13.2). As might be anticipated, within-country of estimates instructional time can vary somewhat from the levels of instructional time established by policy.

The eighth grade students across the TIMSS 2019 countries received an average of 1,023 hours of instruction across all subjects; 137 hours, or about 13 percent of the total, were devoted to science instruction. The number of hours for science instruction ranged from 243 in Lebanon, where science is taught as separate subjects, to 70 in Italy. In nearly all of the countries that participated in TIMSS at the fourth and eighth grades, the number of hours devoted to science instruction increased between fourth and eighth grades—sometimes by three or more times the average hours in fourth grade—reflecting the increased emphasis on science in the curriculum by the eighth grade.

Exhibit 13.3 also includes, for countries teaching separate science subjects, the average number of hours for biology, chemistry, physics, and Earth science. In this subset of countries, students had an estimated 181 hours of science instruction. On average, the highest number of annual hours were devoted to instruction in physics (52 hours), followed by chemistry (51 hours), biology (45 hours), and Earth science (40 hours).

The science content domains and underlying topic areas assessed in TIMSS 2019 are documented in the TIMSS 2019 Science Framework, which was developed in collaboration with the participating countries. The science topics included in the TIMSS assessments do not represent the intersection of the topics that are universally taught but rather are a forward-looking conception of science teaching and learning.

Exhibit 13.4 (see About the Scale) shows the science content domains—life science, physical science, and Earth science—and the 26 underlying topics in the TIMSS fourth grade science assessment. There were 7 topics in life science, 12 in physical science, and 7 in Earth science. Exhibit 13.6 (see About the Scale) shows the same information for the eighth grade science assessment, with its four content domains—biology, chemistry, physics, and Earth science, and the 26 underlying topics. There were 7 topics in biology, 8 in chemistry, 7 in physics, and 4 in Earth science. Teachers were asked to indicate, for each topic, whether it had been “mostly taught before this year” to students in the assessed class or “mostly taught this year,” or had been “not taught or just introduced” to students. This information serves as an indicator of the “implemented curriculum.” It can be examined together with information provided by TIMSS National Research Coordinators about whether each of the TIMSS 2019 science topics was included in their countries’ intended curriculum through the fourth or eighth grade and, if so, whether the topics were intended to be taught to “all or almost all students” or “only the more able students.” This information about the intended curriculum is reported in the TIMSS 2019 Encyclopedia.

Exhibit 13.5 presents fourth grade teachers’ reports about the TIMSS science topics that had been taught to students in fourth grade classrooms either prior to or during the year of the TIMSS assessment. The exhibit shows, for each country and the international average, the percentage of students whose teachers reported that the students had been taught each of the topics (before or during the school year), averaged across all topics in each science content domain, and also across all topics in all science domains. Exhibit 13.7 presents parallel information for the eighth grade, reported by teachers about the TIMSS science topics in the eighth grade assessment.

In the fourth grade, according to their teachers, 62 percent of students, on average, had been taught the TIMSS science topics overall. On average, 73 percent of students had been taught the TIMSS life science topics, and 58 percent and 60 percent had been taught the TIMSS physical science and Earth science topics, respectively. There was, however, considerable variation from content domain to content domain and from country to country, reflecting differing science curricular emphases.

In the eighth grade, on average, 72 percent of students had been taught the TIMSS science topics overall, according to their teachers. Close to three-quarters, on average, had been taught the TIMSS biology topics (74%) and chemistry topics (74%) by the eighth grade, according to their teachers, with slightly less having been taught the Earth science (71%) and physics (68%) topics. There was considerable variation across countries with respect to topic coverage by content domain.

The clarity with which teachers convey the curriculum to students has significant implications for student learning. Students were asked about aspects of teachers’ instruction during their science lessons: whether they know what their teacher expects them to do, and whether their teacher is easy to understand, has clear answers to their questions, is good at explaining science, does a variety of things to help the students learn, links new lessons to previous knowledge (eighth grade only), and explains a topic again when the students do not understand. Responses were combined into the TIMSS 2019 Instructional Clarity in Science Lessons scale, as described in Exhibit 13.8 (see About the Scale). Exhibits 13.9 and 13.10 present students’ reports about the clarity of their science lessons, for fourth grade and eighth grade, respectively. Countries are reported by percentage of students reporting “high clarity of instruction.”

On average, slightly less than three-quarters (72%) of fourth grade students reported “high clarity” of instruction in their science lessons, 22 percent reported “moderate clarity,” and just 6 percent characterized their lessons as having “low clarity.” There was a range in views across countries with, interestingly, lower percentages of students characterizing their lessons as having “high clarity” in some of the higher performing countries, such as Korea and Japan. On average, internationally and within most countries, however, higher clarity was associated with higher average achievement. Across countries, average achievement was 498 among students reporting “high clarity” of instruction, 480 among students reporting “moderate clarity” of instruction, and 466 among students reporting “low clarity” of instruction.

Eighth grade students’ reports are presented separately for countries in which science is taught as an integrated subject in eighth grade (first panel of the exhibit) and for countries in which science is taught as separate subjects (following four panels). Eighth grade students were, on average, less positive about the clarity of their science instruction compared with fourth grade students. Similar percentages of students reported “high,” “moderate,” and “low clarity of instruction” for integrated science, biology, chemistry, physics, and Earth science. For all science subjects, 44 to 49 percent of eighth grade students, on average, characterized instruction as having “high clarity,” 38 to 41 percent reported “moderate clarity,” and 12 to 16 percent reported “low clarity.” As seen in fourth grade, clarity of instruction was positively associated with science achievement. In countries teaching science as an integrated subject and for each of the separate science subjects, average achievement increased with each successively higher level of students’ reports of instructional clarity.

Science practices, and in particular scientific inquiry and investigation knowledge and skills, are important components of many science curricula. Teachers were asked the frequency with which they have their students engage in various instructional activities related to science investigations and experiments. Responses were combined into the TIMSS Teachers’ Emphasis on Science Investigation scale, described in Exhibit 13.11 (see About the Scale), to report two categories: “about half the lessons or more” and “less than half the lessons.” Results of teachers’ reports are presented in Exhibits 13.12 and 13.13 for fourth and eighth grades, respectively, together with students’ average achievement. Countries are ordered by the percentage of students in “about half the lessons or more.”

On average, 31 percent of fourth grade students had teachers who reported an emphasis on science investigation in “about half the lessons or more,” and 69 percent had teachers who reported an emphasis on science investigation in “less than half the lessons.” Average achievement was similar for students in both categories of emphasis. Just 27 percent of eighth grade students were taught by teachers reporting an emphasis on science investigation in “about half the lessons or more,” and 73 percent had teachers who reported an emphasis on science investigation in “less than half the lessons.” In eighth grade, average achievement for students in the “about half the lessons or more” category was 492, and was 490 for those in the “less than half the lessons” category.

Undertaking hands-on science investigations is an important component of science curricula in many countries. Exhibits 13.14 (fourth grade) and 13.15 (eighth grade) present principals’ reports on whether their schools have two resources for facilitating hands-on science experiments—a science laboratory and assistance for teachers when students are conducting experiments—along with student achievement. Countries are ordered by the percentage of students in schools with a science laboratory.

On average across countries, 36 percent of fourth grade students were in schools with a science laboratory, and their average achievement was higher than that of the 64 percent of students who were in schools without a laboratory (496 vs. 486). Of course, the availability of a laboratory in the school could be related to other economic factors that are related to achievement. On average, 35 percent of fourth grade students were in schools in which assistance is available to teachers when students are conducting experiments. This finding also ranged considerably across countries, and there are countries in which many schools have a science laboratory, but assistance is not available to teachers when students conduct experiments.

A much higher percentage of eighth grade students (85%) were in schools with a science laboratory. Average achievement for these students was substantially higher than for students in schools without this resource (494 compared with 457). Still, only about half (54%) of students were in schools in which assistance was available to teachers when students are conducting experiments, and this finding was likewise associated with higher average science achievement (494 compared with 483).

Students were asked about the frequency with which they conduct science experiments in their science lessons. Their reports are presented in Exhibits 13.16 (fourth grade) and 13.17 (eighth grade).

In fourth grade, 31 percent of students, on average, reported that they conducted experiments “at least once a week,” 26 percent “once or twice a month,” 24 percent “a few times a year,” and 18 percent “never.” Across countries, students reporting that they do experiments “once or twice a month” or “a few times a year” had higher average achievement than students who said they do them “at least once a week” or “never.”

In the eighth grade, the frequency with which students conduct science experiments varied by science subject. In countries teaching science as an integrated subject, 28 percent of students reported that they do them “at least once a week,” 37 percent said “once or twice a month,” 24 percent said “a few times a year,” and 11 percent said they “never” do them, on average. In countries teaching science as separate subjects, frequencies were similar to those for integrated science in chemistry and physics lessons, but much less frequent in biology and Earth science lessons. As in fourth grade, across countries, students reporting that they do experiments “once or twice a month” or “a few times a year” had higher average achievement than students doing them “at least once a week” or “never.”

Information about students’ access to computers as part of their mathematics and science lessons is provided in Exhibits 14.1 (fourth grade mathematics), 14.2 (fourth grade science), 14.3 (eighth grade mathematics), and 14.4 (eighth grade science). Each exhibit presents teachers’ reports on whether computers are available for students to use during lessons as well as the types of access they have: whether each student in the class has a computer, the class has computers that students can share, and/or the school has computers that the class can sometimes share (teachers could indicate more than one type of access to computers). Average student achievement is also reported for each category. Countries are ordered by the percent of students having access to computers.

In fourth grade, computers are available for students to use during mathematics lessons for 39 percent of students, on average (Exhibit 14.1), and during science lessons for 45 percent of students, on average (Exhibit 14.2). Availability of computers during mathematics and science lessons was similar for eighth grade students: 37 percent had mathematics teachers who said computers were available (Exhibit 14.3) and 48 percent had science teachers who said computers were available (Exhibit 14.4). There was wide variation across countries in computer availability, with 80 percent or more of students having access in some countries and as few as 5 or 6 percent in others. Having computers available for instruction was associated with higher achievement, on average, in both mathematics and science and at both grades. Of course, access to computers is likely associated with access to other resources that are associated with higher achievement. There was also quite a bit of variation across countries in the types of access to computers, though the most frequent type of access was that the school has computers that the class can sometimes use (28–29% of students in mathematics lessons and 36–39% of students in science lessons).

Exhibits 14.5, 14.6, 14.7, and 14.8 presents teachers’ reports on the frequency they do activities on computers to support learning during mathematics and science lessons, together with average achievement by frequency. Across both grades and subjects, 5 to 9 percent of students on average are in classes in which their teacher reported doing computer activities to support learning “every day or almost every day,” 10 to 14 percent had teachers who reported “once or twice a week,” 13 to 21 percent “once or twice a month,” and 56 to 68 percent “never or almost never.”

Teachers reported doing computer activities more frequently in science lessons than in mathematics lessons. Although 60 percent of fourth grade students (Exhibit 14.6) and 56 percent of eighth grade students (Exhibit 14.8) had science teachers who said they “never or almost never” did computer activities to support learning, 67 percent of fourth grade students (Exhibit 14.5) and 68 percent of eighth grade students (Exhibit 14.7) had mathematics teachers who reported “never or almost never” doing computer activities to support learning. Though few students are in classes where computers are used on a frequent basis, there was a substantial range across countries. For example, in fourth grade mathematics, on average only 7 percent of students’ mathematics teachers said they use computers to support learning “every day or almost every day,” on average, but more than 25 percent did so in Denmark, the Netherlands, New Zealand, and the United States.

Students in classes where teachers “never or almost never” used computers to support learning had the lowest achievement, on average. At both the fourth and the eighth grades, there was a 10-point difference in average mathematics achievement as well as average science achievement between students in the two lowest categories. Beyond that, the relationship with achievement varied across grades and subjects. In fourth grade mathematics (Exhibit 14.5) and eighth grade science (Exhibit 14.8), students with teachers who did computer activities “every day or almost every day” had the highest average achievement compared to students in the other three categories (515 vs. 509, 510, and 500 for fourth grade mathematics; 509 vs. 495, 497, and 487 for eighth grade science), while in fourth grade science (Exhibit 14.6), average achievement was similar for students in the “every day or almost every day,” “once or twice a week,” and “once or twice a month” categories (498, 498, and 500, respectively). In eighth grade mathematics (Exhibit 14.7), students in the two highest frequency categories had the same average achievement (505), which was higher than for students in the “once or twice a month” (497) and “never or almost never” (487) categories.

Exhibits 14.9, 14.10, 14.11, and 14.12 present teachers’ reports on the frequency with which students take mathematics and science tests on computers or tablets. On average, 61 to 69 percent of fourth and eighth grade students “never” take mathematics and science tests on computers or tablets according to their teachers, 14 to 21 percent do so “once or twice a year,” and 17 to 20 percent do so “once a month or more.” At the fourth grade, taking tests on digital devices was slightly less common in science compared to mathematics, with 69 percent of students “never” taking them and just 14 percent taking them “once a month or more,” compared to 64 percent and 18 percent in mathematics, respectively. There is tremendous variation across countries, however, with a number of countries at both grades having 90 percent or more of students “never” taking mathematics and science tests on digital devices, and some countries having about half or more of students doing so “once a month or more.”

The relationship between the frequency of taking tests on digital devices and average achievement varied across grades and subjects. At the eighth grade (Exhibits 14.11 and 14.12), although taking mathematics tests on computers “once a month or more” was associated with lower average achievement than “once or twice a year” and “never” (482 vs. 494 and 491, respectively), average achievement was similar across the three categories for taking science tests (492, 496, and 491, respectively). Average achievement was also similar across the three categories at the fourth grade (Exhibits 14.9 and 14.10), for both mathematics tests (502, 504, and 501, respectively) and science tests (489, 491, and 491, respectively).