TIMSS 2015 Results

Achievement scales
Scale creation

The TIMSS international achievement scales were developed on the basis of item response theory and population models using plausible values, with each student respondent being assigned five plausible values on each of the achievement scales.

Scale scores range from 0 to 1000.

Each international scale was established by TIMSS 1995 to have a midpoint of 500 located at the mean of the combined achievement distribution across all countries and 100 scale score points corresponding to one standard deviation of the combined distribution.

In order to measure trends over time, the results of all subsequent TIMSS assessments (1999, 2003, 2007, 2011, and 2015) were transformed into this metric.


Overview of achievement scales
  • Overall achievement (Mathematics and Science, Grades 4 and 8)
  • Content domains
    • Mathematics
      • Grade 4: numbers, geometric shapes and measures, data display
      • Grade 8: numbers, algebra, geometry, data and chance
    • Numeracy
      • Grade 4: whole numbers, fractions and decimals, shapes and measures
    • Science
      • Grade 4: life science, physical science, earth science
      • Grade 8: biology, chemistry, physics, earth science
  • Cognitive domains (Mathematics and Science, [Grades 4 and 8] Numeracy, Grade 4)
    • Knowing
    • Applying
    • Reasoning

Overall achievement results were reported in terms of the percentages of students reaching the following four benchmarks:

  • Advanced International Benchmark (625)
  • High International Benchmark (550)
  • Intermediate International Benchmark (475)
  • Low International Benchmark (400)

The descriptions of the competencies of students reaching each of these benchmarks were determined by means of a scale-anchoring process.

Background scales
scale creation

TIMSS 2015 created a variety of background questionnaire scales to report the context questionnaire data.

Context questionnaire items were developed to be combined into scales measuring a single underlying latent construct.

Scales were calculated using item response theory (IRT), specifically a Rasch partial credit model.

In addition, categorical variables were created using these scales by classifying respondents into one of three groups: High, Middle, and Low. Cut-off points for categorization were determined on a scale-by-scale basis.

For certain scales that maintained many of the same items across TIMSS 2011 and TIMSS 2015, the scales were linked to allow for trend measurement on the background construct.

Questionnaire scales
  • Home Environment Support
    • Could Do Early Literacy and Numeracy Tasks When Began Primary School (Mathematics and Science, Grade 4)
    • Early Literacy and Numeracy Activities Before Beginning Primary School (Mathematics and Science, Grade 4)
    • Home Resources for Learning (Mathematics and Science, Grade 4)
    • Home Educational Resources (Mathematics and Science, Grade 8)
    • Parental Attitude Toward Mathematics and Science
    • Parents’ Perceptions of School Performance
  • School Resources (Mathematics and Science, Grades 4 and 8)
    • Instruction Affected by Mathematics Resource Shortages
    • Instruction Affected by Science Resource Shortages
    • Problems with School Conditions and Resources
  • School climate (Mathematics and Science, Grades 4 and 8)
    • School Emphasis on Academic Success – Principals’ Reports
    • School Emphasis on Academic Success – Teachers’ Reports
    • Safe and Orderly School
    • School Discipline Problems
    • Student Bullying Scale
    • Students’ Sense of School Belonging (Grades 4 and 8)
    • Schools Where Students Enter the Primary Grades with Literacy and Numeracy Skills
  • Students’ attitudes
    • Students Like Learning Mathematics/Science (Mathematics and Science, Grades 4 and 8)
    • Students Like Learning Biology (Science, Grade 8)
    • Students Like Learning Chemistry (Science, Grade 8)
    • Students Like Learning Physics (Science, Grade 8)
    • Students Like Learning Earth Science (Science, Grade 8)
    • Students Confident in Mathematics/Science (Mathematics and Science, Grades 4 and 8)
    • Students Confident in Biology (Science, Grade 8)
    • Students Confident in Chemistry (Science, Grade 8)
    • Students Confident in Physics (Science, Grade 8)
    • Students Confident in Earth Science (Science, Grade 8)
    • Students Value Mathematics/Science (Mathematics and Science, Grade 8)
    • Students Value Biology (Science, Grade 8)
    • Students Value Chemistry (Science, Grade 8)
    • Students Value Physics (Science, Grade 8)
    • Students Value Earth Science (Science, Grade 8)
  • Instruction
    • Students Views on Engaging Teaching in Mathematics/Science Lessons (Mathematics and Science, Grades 4 and 8)
    • Students Views on Engaging Teaching in Biology Lessons (Science, Grade 8)
    • Students Views on Engaging Teaching in Chemistry Lessons (Science, Grade 8)
    • Students Views on Engaging Teaching in Physics Lessons (Science, Grade 8)
    • Students Views on Engaging Teaching in Earth Science Lessons (Science, Grade 8)
    • Teachers Emphasize Science Investigation (Science, Grades 4 and 8)
    • Teaching Limited by Student Needs (Grades 4 and 8)
    • Challenges Facing Teachers (Mathematics and Science, Grades 4 and 8)
    • Teacher Job Satisfaction (Mathematics and Science, Grades 4 and 8)
Overview of key study results

Mathematics and Science

  • Countries
    • East Asian countries were the top performers in Grades 4 and 8 in mathematics.
    • Singapore and Korea were the top achievers in fourth-grade science; Japan, the Russian Federation, and Hong Kong SAR were also among the top five.
    • Singapore was the top achiever in science, followed by Japan, Chinese Taipei, Korea, and Slovenia.
    • A very high percentage of East Asian students met or exceeded the TIMSS international benchmarks.
  • Achievement and gender
    • Boys had higher mathematics achievement in more countries than girls.
    • No difference was found between boys and girls in science achievement in more than half the countries.
  • Trend (1995–2015)
    • In both grades the trends show increases in mathematics and science achievements around the world.
    • More students than ever were able to reach the highest levels of achievement.
    • Twenty-year trends show a reduction in boys’ advantage in science achievement.
    • Curricula have changed across the globe over the course of 20 years of TIMSS testing.


Context for Education

  • Parents and home resources
    • Students whose parents reported often spending time with them on early literacy and numeracy learning activities had higher levels of mathematics and science achievement at the fourth grade.
    • Students whose parents reported many home resources for learning had higher levels of achievement than students whose parents reported some or few resources.


  • Teachers and teaching; principals
    • Teachers had a high degree of job satisfaction.
    • Teachers and principals reported high levels of education and considerable experience.
    • Instructional time remains a crucial resource in considering students’ opportunity to learn, even though there are many factors that influence the effectiveness of an educational system. There was considerable range in the yearly number of instructional hours in mathematics.


  • Student (preprimary) preparation and attitudes toward learning
    • There was a positive relationship for fourth-grade students between the number of years students attended preprimary education programs and their mathematics and science achievement.
    • Students in the fourth grade performed better in schools where entering students have already acquired key skills.
    • Students start out confident in mathematics and science at the fourth grade, but that feeling erodes by the eighth grade.
    • Most students felt they fit in at school.
    • Students liked their mathematics and science instruction—a lot.


  • School environments and safety
    • In nearly all TIMSS 2015 countries, students attending schools with more affluent than disadvantaged students had higher average mathematics and science achievement scores.
    • Generally, students were in positive school environments according to their principals, teachers, and the students themselves
    • With the emergence of cyberbullying, school-related bullying is a growing concern.
    • Schools have become safer places overall.