Australia participated in the eighth cycle of the Trends in International Mathematics and Science Study (TIMSS). TIMSS is an international sample study that assesses the mathematics and science achievement of Year 4 and Year 8 students every 4 years. Australia has participated in all cycles of TIMSS since it commenced in 1995 and over this 28-year period has collected rich data about trends in mathematics and science achievement. TIMSS 2023 expanded its scope to assess environmental knowledge and attitudes. This new component provides valuable insights into students' understanding of environmental issues, including climate change, biodiversity, and conservation. This Highlights report summarises the key findings from "TIMSS 2023 Australia. Volume I: Student performance," where detailed information about the background and management of TIMSS 2023 is also available.