Number
The real number system comes into focus: rational and irrational numbers, how they sit together on the number line, and how to work with both when solving problems.
Home / Curriculum / Year 9 Mathematics
Year 9 · Mathematics · Western Australian Curriculum
The steepest climb in school maths, and the most rewarding.
Year 9 is the steepest single step in secondary mathematics. Algebra deepens into quadratics, triangles give up their secrets to trigonometry, and NAPLAN gives an external read on how it is all going. It is a demanding year, and also the one where genuine mathematical confidence is made.
Where Year 9 sits in the journey
In the WA curriculum journey, Year 9 is where mathematics becomes visibly abstract. The index laws learnt with numbers now apply to algebra, binomial products and simple quadratics appear, and the Cartesian plane becomes a genuine workspace with gradients, midpoints and distances. Trigonometry arrives through the geometry of similar triangles, and measurement stretches to scientific notation and percentage error. It is a dense year by design, and it rewards students who arrive with their Year 8 toolkit intact.
What the curriculum covers
Inside Year 9 Mathematics in WA.
Algebra
Index laws extend from numbers to variables, binomial products get expanded, and simple quadratic expressions get factorised. Graphs of quadratics introduce the curve that dominates senior maths.
Measurement
Surface area and volume of prisms and cylinders, scientific notation for the very large and very small, and percentage error, because every measurement is an estimate. Pythagoras teams up with trigonometry to find unknown sides and angles.
Space
Trigonometry is born here, from a beautiful fact: right-angled triangles with the same angles always have the same side ratios. Enlargement and scale connect geometry to maps, models and design.
Statistics
Comparing whole data sets rather than single numbers, and asking hard questions about how surveys reported in the media gathered their data and whether their claims hold up.
Probability
Multi-step chance events, with and without replacement, mapped completely with tree diagrams, tables and arrays so probabilities can be calculated instead of guessed.
This year, your child will
Real growth you can watch happen.
Year 9 results shape decisions in a way earlier years do not. A strong result in Year 9 NAPLAN numeracy can meet the WACE numeracy requirement early and lift a weight off the senior years, and how a child handles quadratics and trigonometry now heavily influences which Year 11 courses will feel realistic. Just as importantly, this is the year many students privately decide whether they are a maths person. The right support at the right moment changes that story.
- ✓Apply the index laws to algebraic expressions, not just numbers
- ✓Expand binomial products and factorise simple quadratics
- ✓Calculate gradients, midpoints and distances on the Cartesian plane
- ✓Use sine, cosine and tangent to find missing sides and angles in right-angled triangles
- ✓Express tiny and enormous measurements in scientific notation
- ✓Map compound chance events completely with tree diagrams and arrays
How Sorsa supports Year 9 Mathematics
Built to meet your child exactly where they are.
Study maps directly onto what Western Australian schools assess in Year 9, so no effort is wasted on content written for other states.
Practice scales from rebuilding confidence to genuine extension, which matters most in a year this steep.
As a parent you get an honest window into what is being practised and how it is going, without needing to ask twice.
Questions parents ask
Year 9 Mathematics, answered.
What maths is covered in Year 9 in WA?
Year 9 covers the real number system, index laws applied to algebra, expanding binomials and factorising simple quadratics, coordinate geometry with gradient, midpoint and distance, graphs of quadratic functions, surface area and volume of prisms and cylinders, scientific notation, similarity and scale, trigonometry in right-angled triangles, comparing data distributions, and compound probability.
How does Year 9 NAPLAN relate to OLNA in WA?
Students whose Year 9 NAPLAN numeracy result reaches the cut point score set by SCSA prequalify for the WACE numeracy standard and do not sit the OLNA numeracy test. Students who do not prequalify get several opportunities to pass OLNA from Year 10 onwards. A well-prepared Year 9 can quietly remove an entire hurdle from the senior years.
When do students start trigonometry in WA schools?
Trigonometry begins in Year 9, where students discover that the side ratios of right-angled triangles depend only on their angles, and learn to use sine, cosine and tangent. Year 10 extends it to practical problems involving direction and angles of elevation and depression, and the senior ATAR courses build well beyond that.
Is Year 9 the hardest year of high school maths?
Many teachers would say yes, because the jump in abstraction is real: quadratics, trigonometry and formal coordinate geometry all land in the same year. The good news is that difficulty here is usually about missing Year 8 tools rather than ability. Diagnose the gaps, close them patiently, and the year becomes challenging in the satisfying way rather than the discouraging one.
Launching soon
Give your child the head start you wished you had.
Sorsa opens to Western Australian families soon. Join the parent waitlist for launch access and early supporter pricing.
Mathematics in other years
More Year 9 subjects