IEA’s TIMSS is the world’s longest-running global assessment of student achievement in mathematics and science. Directed by the TIMSS & PIRLS International Study Center at Boston College, TIMSS has monitored trends in mathematics and science achievement around the world since 1995, gathering high-quality data that policymakers and educators use to make evidence-based decisions about education systems and curricula. TIMSS 2019 was the 7th cycle of TIMSS, providing 24 years of trend data monitoring progress in student achievement at the fourth and eighth grades. TIMSS provides critical information about what students know and can do in mathematics and science as countries work to prepare youth for a world in which both mathematics and science play an increasingly important role in helping to solve global challenges. The health of our planet depends on upcoming generations that can be leaders in technological innovation and that can participate in a global society prepared to protect our environment and well-being. In 2019, 64 countries and 8 benchmarking systems participated in TIMSS and, altogether, nearly 600,000 students were assessed. The TIMSS mathematics and science assessments are based on countries’ shared expectations of what students should know and be able to do and included almost 1,000 mathematics and science achievement items. TIMSS 2019 also marked the beginning of the transition to digital assessment, enabling TIMSS to include more interactive and innovative item types that engage students. About half of the participating countries administered the eTIMSS version of the assessments. In fourth grade mathematics, Singapore was the top-performing country. Together with Hong Kong, Korea, Chinese Taipei, and Japan, the East Asian countries led the other TIMSS countries by a substantial margin. A 26-point gap set them apart from the next highest scoring countries. At the eighth grade, the five East Asian countries again outperformed the rest of the countries: Singapore, Chinese Taipei, and Korea, followed by Japan and then Hong Kong. The gap between these countries and the rest was even greater at 35 score points. Results for science were a little different, especially at the fourth grade. In fourth grade science, Singapore and Korea had the highest average achievement, followed by a 21 point gap before the Russian Federation and Japan. Chinese Taipei and Finland also performed very well. At eighth grade, Singapore was the top performer, scoring 34 points higher than Chinese Taipei, Japan, and Korea. The Russian Federation and Finland and the rest of the countries followed after an 18 point gap. To describe the kinds of mathematics and science that fourth and eighth grade students know and can do, TIMSS reports achievement at four international benchmarks: Low, Intermediate, High, and Advanced. Students at the Low Benchmark only have some basic knowledge of the subject. In contrast, students at the Advanced Benchmark can apply their understanding and knowledge in a variety of relatively complex situations and explain their reasoning. For the 58 countries participating at the fourth grade, most are educating their students beyond minimum proficiency in mathematics and science, with 92 percent of students across countries reaching the Low Benchmark in both subjects. Only 6-7 percent of students met the Advanced Benchmarks. Not surprisingly, the highest performing countries in terms of average scores also had the highest percentages of students reaching the Advanced Benchmark. For example, in Singapore, 54 percent of fourth grade students met the Advanced Benchmark in mathematics. Across the 39 countries at the eighth grade, 85 to 87 percent of students reached the Low Benchmarks. Only 5 to 7 percent reached the Advanced Benchmarks. In comparison, building on its top achievement in mathematics at fourth grade, Singapore also had 51 percent of its eighth grade students reach the Advanced Benchmark. For over 24 years, TIMSS data have been an invaluable tool to policymakers and educators around the world as they evaluate their education systems. TIMSS data are used to spur new education initiatives, and to later gauge the effectiveness of those initiatives. Recent trends compare average achievement in TIMSS 2019 to average achievement in 2015. Longer-term trends look at changes in average achievement since the inception of TIMSS in 1995. In fourth grade mathematics, both recent and long-term trends show more countries with improvements than declines in average achievement. Short-term trends show 14 of the 45 participating countries had higher average achievement in TIMSS 2019 than in 2015 compared to 8 with declines, and 23 staying the same. Of the 16 countries that participated in 1995, 13 improved, 2 remained stable, and only 1 declined. Similarly, average mathematics achievement at the eighth grade improved in more countries than it declined over both the short term and the long term. In the short term, 13 countries improved, 16 were stable, and 4 declined. In the long-term, 9 countries improved, 5 were unchanged, and 4 decreased. In fourth grade science, the short-term trends from TIMSS 2015 showed a less positive pattern than in mathematics--an equal number of 10 improvements and 10 declines, with 24 countries staying the same. However, the long term trends from 1995 in science were similar to mathematics, 11 countries improved, 3 were unchanged, and 2 decreased. Also, the science trends at eighth grade showed more improvements than declines in both the short-term and the long-term. Since 2015, 11 countries improved, 17 were stable, and 5 countries declined. In the long term, 8 countries improved, 6 were unchanged, and 4 declined. In fourth grade mathematics, 27 countries had no gender gap in average achievement, but boys outperformed girls in another 27 countries. This is due, in part, to 9 countries developing a gender gap favoring boys since the last TIMSS cycle in 2015. In 2019, girls outperformed boys in 4 countries. Gender equity was more prevalent in eighth grade mathematics, with 26 countries experiencing no gender gap. Boys outperformed girls in 6 countries, and girls outperformed boys in 7 countries. In fourth grade science, there was gender equity in average achievement in 33 countries. Girls outperformed boys in 18 countries compared to boys outperforming girls in 7 countries. In eighth grade science, there was gender equity in 18 countries, but girls had higher average achievement than boys in 15 countries, nearly as many. Boys outperformed girls in 6 countries. This video presents TIMSS 2019 country comparisons in mathematics and science achievement and trends in achievement at the fourth and eighth grades. To view a video about home, school, and classroom contexts for mathematics and science teaching and learning and to find about more about the TIMSS 2019 international results, visit timss2019.org. TIMSS is a project of IEA and is directed by the TIMSS & PIRLS International Study Center at Boston College.