reSolve Maths by Inquiry (K-6) IA collaboration of the Australian Academy of Science and the Australian Association of Mathematics Teachers. The tasks and materials on reSolve promote fluency, deep understanding, strategic problem solving, and mathematical reasoning through enquiry.
NRICH (K-6) NRICH provides thousands of free online mathematics resources for ages 3 to 18, covering all stages of early years, primary and secondary school education with a focus on developing mathematical thinking and problem-solving skills (University of Cambridge).
Moneysmart.gov.au Free, engaging, curriculum-aligned classroom resources.