The Trends in International Mathematics and Science Study (TIMSS) explores how well students have mastered the knowledge and skills they’re taught in school. A new insights report on the latest assessment cycle investigates how much curriculum content is actually covered in classrooms, and whether differences are linked to student achievement.
TIMSS is a large-scale assessment that analyses national year 4 and year 8 mathematics and science curricula, then tests students on common content across participating countries to enable a fair comparison. The IEA report (Kalaycioglu et al., 2026) focuses on year 8 mathematics and science. Drawing on data from TIMSS 2023 – including student performance and teacher questionnaire responses – it explores how curriculum expectations, classroom instruction and learning outcomes align.
From curriculum to classroom
The core of this issue relates to 3 interconnected layers of curriculum: the intended curriculum (what education systems expect to be taught), the implemented curriculum (what teachers actually teach), and the attained curriculum (what students have learned).
‘Curricular changes must be implemented effectively in classrooms to have the desired effects. However, some research has found that a significant portion of intended curriculum content often goes unimplemented,’ the report explains. ‘Conceptually complex or abstract topics, along with reasoning tasks, technology-integrated components, experimental or hands-on activities, end-of-year content, and material not aligned with high-stakes assessments, are least likely to be implemented.’
International findings – 3 takeaways
The intended curricula of participating countries largely align with what TIMSS expects students to learn by year 8. ‘This was the case for both subjects, although alignment between the framework topics and national curricula was stronger within mathematics than within science,’ the report notes. In mathematics, there was particularly strong alignment in the Number content domain while Data and Probability showed more variation across countries. In Science, the greatest variation across countries was in Earth Sciences, which the report says may be due to topics being included in other subjects, such as Geography.
When it came to within-country alignment between the intended (expected) and implemented (taught) curricula, in mathematics it was high for Number, and Geometry and Measurement but there were potential implementation gaps in some systems in Algebra, and Data and Probability topics. In Science, there was high alignment for Biology and Chemistry, but in Physics ‘many national curricula covered a broader set of topics than teachers reported teaching to students, perhaps reflecting the challenging nature of the subject’. Earth Sciences was another area of low alignment for many countries.
One of the most important findings is that teaching more topics doesn’t automatically lead to better student outcomes. The report notes, as other research has shown, ‘breadth of topic coverage alone does not appear to be a driver of student achievement in many countries.’ In other words, the curriculum is just the start – it’s about how the content is taught, teachers knowing the needs of their students, and how they support them in their learning, particularly with more challenging, cognitively demanding or abstract concepts.
What the findings show for Australia
Consistent with the international findings, Australia’s curriculum broadly aligns with what TIMSS expects students to learn by year 8, but more so in mathematics than science.
Mathematics: Teachers report very strong coverage of Number, strong coverage of Data and Probability, and high coverage of Geometry and Measurement. Algebra stands out as the weakest topic, suggesting more foundational mathematics content is being prioritised in the classroom.
Science: Teachers report relatively high alignment in Biology, and Chemistry. There are larger gaps in Physics and Earth Science, with Physics the most challenging area to deliver consistently.
On content breadth versus outcomes, Australia again mirrors the broader international picture, with no strong relationship between the number of topics taught and student achievement.
Curriculum flexibility
The Australian Council for Educational Research (ACER) manages Australia’s participation in the TIMSS assessment on behalf of the Commonwealth, state and territory governments.
Commenting on the Australian findings, ACER Senior Research Fellow Nicole Wernert says there are a couple of points to note regarding the curriculum. Firstly, the analysis of the degree to which the Australian Curriculum covers TIMSS topics was based on version 8.4, so these results might differ for Version 9. Secondly, the Australian Curriculum is intended to be used flexibly by schools to meet the needs and interests of students in their context. ‘Schools implement the Australian Curriculum in ways that value teachers’ professional knowledge, reflect local contexts and take into account individual students’ family, cultural and community backgrounds,’ (ACARA, 2026).
‘The findings of this report support that flexibility given the extremely weak link between the number of topics covered and student achievement in mathematics and science,’ Wernert says, adding, ‘Therefore, the curriculum stands as a guide to what to cover and when, but teachers and school leaders are then able to take into account the students that they have in front of them and adapt their implemented curriculum and classroom activities to those students' learning needs and interests.’
Areas for further research
The report identifies several priorities for future research, including exploring not just how many topics are covered in the classroom but also their complexity and cognitive demand. It also suggests broadening the analysis to include how instructional practices, student attitudes, and learning experiences in and outside the classroom (including tutoring or other informal support) shape achievement.
References
ACARA. (2026). Australian Curriculum Version 9.0. Implementation of the Australian Curriculum. https://www.australiancurriculum.edu.au/help/f-10-curriculum-overview/implementation-of-the-australian-curriculum0
Bakan Kalaycioglu, D., Reynolds, K. A., Fishbein, B., Gonzalez, E., & von Davier, M. (2026). Intended, implemented, and attained mathematics and science curricula at the eighth grade: Findings from TIMSS 2023. Boston College, TIMSS & PIRLS International Study Center. https://doi.org/10.6017/lse.tpisc.timss.wf9486
Thinking about your own context and subject area, which areas of the curriculum are consistently well covered? Where might there be gaps?
Which topics do your students tend to struggle with? How does this influence your teaching focus and content coverage? What teaching approaches have you used to support learning in more challenging, cognitively demanding or abstract topics?
