Year 4 Science: Every Australian Curriculum Code, Explained

Year 4 Science in the Australian Curriculum is twelve content descriptions, and eight of them are word for word identical to Year 3. The entire Science Inquiry strand and both Science as a Human Endeavour codes repeat verbatim. Only the four Science Understanding codes are new: food chains, the water cycle, forces, and the properties of materials.

That makes Year 4 the second of the two repeat years in primary Science, after Year 2, and it creates the same trap. A program planned only from the content descriptions will be a Year 3 program with four new topics in it, the rise in demand will be invisible until the achievement standard is being reported against, and Year 5 will arrive with the largest single jump in the subject. This is a working guide to all twelve codes: what actually rises when the wording does not, the three descriptors that are hardest to get right, a term-by-term order that uses the Southern Hemisphere seasons, and the checks that tell you whether a student is ready for the Year 5 cliff.

What changes this year

Nothing changes in the inquiry wording, which is precisely the problem. Version 9 pairs the Science Inquiry strand across two-year spans: AC9S1I01 to AC9S1I06 repeat at Year 2, AC9S3I01 to AC9S3I06 repeat at Year 4, and AC9S5I01 to AC9S5I06 repeat at Year 6. The demand rises inside the achievement standard rather than in the descriptors, so you have to plan the rise yourself. Four things should be visibly harder by the end of Year 4 than they were in Year 3.

• The scaffold thins. AC9S4I02 still says “provided scaffolds”, but a Term 4 scaffold should be a heading and a blank space where a Term 1 Year 3 scaffold was a fill-in-the-gap sentence. The word does not change, the amount of paper does.
• Measurement gets finer, not just formal. AC9S4I03 asks for the same formal measurement with familiar scaled instruments. What should rise is reading between the markings, which is exactly what AC9M4M01 in maths asks for this year: interpreting unmarked and partial units.
• Graphs acquire a numerical axis. AC9S4I04 still says “simple column graphs”. Year 3 could satisfy that with one categorical variable and a count. Year 4 should be graphing a measured quantity, because AC9M4ST01 introduces discrete numerical variables and AC9M4ST02 asks students to judge which display works better.
• Fair testing moves from identifying to doing. AC9S4I02 asks students to identify the elements of fair tests. In Year 3 that can be done out loud, after the fact, on somebody else’s investigation. In Year 4 it should be done in writing, before the trial, on their own.

The content half is more straightforward, and there is one structural point worth knowing. AC9S4U03 is the only forces descriptor between Year 1 and Year 7. Pushes and pulls appear at AC9S1U03, forces reappear here, and then nothing until AC9S7U04 introduces balanced and unbalanced forces. Three years of gap on either side. Whatever is not established this year has no scheduled second chance in primary.

The year at a glance

Reading the codes

Science codes are AC9 + S + year + strand letter + number, with U for understanding, I for inquiry and H for human endeavour. Version 9 does not label the Understanding sub-strands, so they are inferred, and Year 4 runs them in the same order as Year 3: AC9S4U01 is biological, AC9S4U02 is Earth and space, AC9S4U03 is physical, AC9S4U04 is chemical.

Strand by strand

Science understanding (AC9S4U01 to AC9S4U04)

Four codes, four unrelated topics, and unlike Year 3 there is no pair that can be collapsed into a single unit. That is worth planning around: Year 3 lets you teach heat and change of state together and get the second code most of the way for free, and Year 4 gives you no such discount. Four topics, four units, roughly a term each.

AC9S4U01 is the year’s load-bearing code, and the part that carries the weight is the word interactions. Naming a producer, a consumer and a decomposer is vocabulary. Explaining their roles and interactions within a habitat, which is what the descriptor asks for, means saying what happens to each one when another is removed. Food chains are then named as a representation of feeding relationships, which puts this code directly in the path of AC9S4I04: a food chain is a visual model, and drawing one is evidence against both codes at once.

AC9S4U02 has a hole underneath it that the curriculum never fills. It asks for the key processes of the water cycle including evaporation and condensation, both of which require water in the gas state. But AC9S3U04 covers the observable properties of solids and liquids only, and gases are not named anywhere until AC9S5U04 in Year 5. So Year 4 students are being asked to track water into and out of a state of matter the curriculum has not introduced. You have to teach that gas concept in this unit, and it is not in any code you can point at. (Victoria closes this gap: the Levels 3 and 4 Victorian Science band names solids, liquids and gases together at VC2S4U04.)

AC9S4U03 names three forces: frictional, gravitational and magnetic. It does not name electrostatic, which surprises people, and it does not name contact and non-contact as categories, although the phrase “exerted by one object on another” is doing that work. Note also what is absent: nothing about balanced or unbalanced forces, which is Year 7, and nothing quantitative at all.

AC9S4U04 is the easiest of the four to under-teach, because it looks like a sorting activity. The descriptor names four material categories (fibres, metals, glass and plastics) and asks students to consider how properties influence use, which is a causal claim rather than a classification. It is also the best content in the year for a genuine fair test, because absorbency, strength and insulation are all measurable with primary equipment.

Science inquiry (AC9S4I01 to AC9S4I06)

Six descriptors identical to Year 3, forming one cycle that should run at least four times. Because the wording gives you nothing to aim at, aim at the Year 5 codes instead. Year 5 is where the scaffolding is withdrawn in a single step, and Year 4 is the last year in which you can rehearse the new grain on content the student already understands.

• AC9S5I01 asks for investigable questions and reasoned predictions. Start rejecting questions that cannot be answered by doing something, and start asking “because?” after every prediction.
• AC9S5I02 asks students to decide the variables to be changed, measured and controlled, to plan repeatable investigations, to describe potential risks, and to identify permissions required for investigations on Country and Place. This is four new obligations replacing “provided scaffolds”, and it is the biggest single increase in the primary Science curriculum.
• AC9S5I03 asks for measurement with reasonable precision, which is what reading between the markings becomes.
• AC9S5I05 asks students to recognise possible sources of error and to select evidence for reasoned conclusions. Year 4 only asks whether the test was fair.

The efficient way to handle all of that is one deliberate bridge unit late in Year 4, described in the term order below, rather than trying to inch every code forward all year.

Science as a human endeavour (AC9S4H01 and AC9S4H02)

Two codes, identical to Year 3, and they are a sequence rather than a pair: data becomes explanation at H01, and explanation becomes application at H02. Repeating them verbatim does not mean repeating the same examples, and the Year 4 content offers two arcs that Year 3 cannot.

The water cycle is the cleanest H01 in primary. Nobody watched a water molecule; the cycle is an explanation assembled entirely out of measurements of rainfall, humidity, river flow and evaporation, which is exactly what the descriptor describes. Forces carry H02 just as cleanly: friction is understood, therefore tyre tread, brake pads, non-slip mats and grip tape exist. Run each arc once, deliberately, and both codes have real evidence behind them instead of a poster about a famous scientist.

The three hardest codes in Year 4

AC9S4U01: which way the arrow points

The misconception: that the arrow in a food chain means “eats”. It means “energy flows to”, so it points from the eaten to the eater, which is backwards from how every student first draws it.

What you will see: a fox drawn with an arrow pointing at a rabbit. Asked to read it aloud, the student says “the fox eats the rabbit”, which is true, and the diagram is wrong. Separately, decomposers are simply absent: students build grass to rabbit to fox and stop, because nothing eats the fox. And “producer” is misheard as the most important animal rather than the organism that makes its own food, so a class will nominate the fox as the producer because it is the top of the chain.

The fix: never say the word “eats” while drawing a chain. Read every arrow out loud as “gives energy to” from the first example, and have students read theirs aloud the same way before it is accepted. For decomposers, ask the question the chain leaves hanging: what happens to the fox when it dies. That single question is the whole justification for the third category, and it turns the chain into a cycle. For producers, use the literal test: can it make its own food. Nothing that has to eat is a producer, and the biggest animal in the picture is always a consumer.

AC9S4U02: where the water on the outside of the glass came from

The misconception: that a gas is nothing, so water that evaporates has ceased to exist, and water that condenses has come from somewhere solid.

What you will see: the classic is the cold glass. Ask where the water on the outside came from and a Year 4 class will say it leaked through, or seeped out, or came from the ice inside. Alongside that: a puddle dried up so the sun drank it, the water soaked into the concrete, or it just went. Asked to point at steam from a kettle, students point at the visible white plume, which is condensed droplets, not steam. Every one of these is the same error, and it is the gap left by gases not being named in Year 3.

The fix: establish that air contains water before you draw a single water cycle diagram. Put a dry glass and a glass of iced water side by side on the same bench and wait: only one gets wet, and the room is the only thing they have in common. Then run the conclusive version, which is a sealed container. Mark the water level in an open dish and a sealed one, leave both in the sun, and weigh the sealed container before and after. The open dish loses water, the sealed one does not, and the sealed one weighs the same, so nothing left it. From there the language to insist on is that water changed state and moved. It never disappears, and it never comes through glass.

AC9S4U03: the ball that runs out of push

The misconception: that motion needs a continuous force to keep it going, so a rolling ball stops when the push it was given runs out. This is the oldest misconception in physics teaching, it is what every human believes before being taught otherwise, and Year 4 is where the curriculum first has the vocabulary to challenge it.

What you will see: asked why a rolling ball stops, students say it ran out of energy, or the push wore off, or it got tired. Friction is either not mentioned or is described as a thing that happens rather than a force something exerts. Asked what forces act on a ball rolling across the floor, students name the push that started it, which is no longer acting at all. The related error is that friction is bad, which makes brakes and tyre tread inexplicable.

The fix: change the question from why it stopped to what stopped it. The first phrasing invites a story about running out; the second demands an object exerting a force, which is the descriptor’s own wording. Then produce the surfaces: the same ball, released from the same height on a ramp, rolling onto carpet, floorboards, a tea towel and a tray of talcum powder. The distances differ enormously, and the ball had the same push every time, so the push cannot be what varied. Make students say which object exerted the force each time. Finish on the bad-friction error by asking them to design a bicycle with as little friction as possible, then to explain how it would stop.

What students need to arrive with

From Year 3 Science, three codes gate this year. AC9S3U01, comparing living and non-living things, is what makes producer and decomposer intelligible, and note the specific gap it leaves: AC9 has no once-living category, so a decomposer eats something students have no word for. AC9S3U04, change of state, is the prerequisite for the water cycle, with the gas caveat above. AC9S3U02, the observable properties of soils and rocks, is what the ground half of the water cycle runs into and what AC9S4U04’s properties work builds on.

Outside Science, maths is the real gate this year, and more so than in Year 3. AC9M4M01 asks students to interpret unmarked and partial units using scaled instruments, which is precisely the precision that AC9S4I03 should be rising to. AC9M4ST01 introduces data for discrete numerical variables and AC9M4ST02 asks students to judge which display is more effective, both of which are what makes AC9S4I04 more than a repeat of Year 3. Our guide to the Year 4 Maths codes covers both. For AC9S4I06 the partner is the Year 4 writing process work in our guide to the Year 4 English codes: the purpose-and-audience clause is the same clause, and it should be taught once rather than twice.

What this year sets up

• Year 5 withdraws the scaffold in one step. AC9S5I01 to AC9S5I06 are all newly worded, and AC9S5I02 alone replaces “provided scaffolds” with deciding variables, repeatable investigations, describing risks and identifying permissions for work on Country and Place. Year 5 then repeats verbatim at Year 6, so the pattern holds: Years 3 and 4 share a grain, Years 5 and 6 share the next one.
• AC9S4U01 (food chains) becomes AC9S5U01, structural features and behaviours enabling survival in specific habitats, and then AC9S6U01, how changing the physical conditions of a habitat affects growth and survival.
• AC9S4U02 (the water cycle) becomes AC9S5U02, weathering, erosion, transportation and deposition. Water is the agent of all four, so the cycle is the mechanism rather than a separate topic.
• AC9S4U03 (forces) has no successor in primary. Physical science continues with light at AC9S5U03 and electrical circuits at AC9S6U03, and forces do not reappear until AC9S7U04 in Year 7, as balanced and unbalanced forces. This is the single strongest argument for giving forces a full term rather than a few weeks.
• AC9S4U04 (properties of materials) becomes AC9S5U04, explaining those properties by modelling the motion and arrangement of particles, and then AC9S6U04, reversible and irreversible change.

A term-by-term order

1. Term 1: the water cycle, while it is hot. AC9S4U02 belongs in February and March, when evaporation is fast enough to see inside a lesson and condensation on a cold glass happens in under a minute. Open with the two glasses, then the sealed and open dishes, and do not draw a cycle diagram until the class agrees that air holds water. Attach AC9S4H01 here: the water cycle is an explanation built entirely out of measurements, which is the descriptor almost word for word. Re-establish the full inquiry cycle at Year 3 grain this term, on procedures students already know.
2. Term 2: food chains, in the leaf litter. AC9S4U01 in autumn, when decomposers are doing visible work. A square metre of leaf litter turned over each week is better evidence than any worksheet, and it makes the third category concrete. This is also the term to push AC9S4I04, because a food chain is itself a visual model and the descriptor explicitly allows visual or physical models: build the chain physically with string between students holding cards, then cut a strand and see what falls over. That is the interactions half of the code, and it cannot be done on paper.
3. Term 3: forces, and fair testing at full grain. AC9S4U03 in the winter term, which is indoor work and needs no weather. Ramps and surfaces make the variable to hold constant obvious, which is why this is the right content for AC9S4I02 in writing and in advance rather than out loud and afterwards. Run the surfaces comparison for friction, drop pairs of objects for gravity, and use magnets for the non-contact case. Close with AC9S4H02: tyre tread, brake pads and grip tape are all friction understood and then applied.
4. Term 4: materials, run at Year 5 grain. AC9S4U04 is the right content for the bridge unit because absorbency, strength and insulation are all measurable, so the investigation can carry the Year 5 requirements without any new science. Run one extended investigation instead of three short ones: students decide which variable to change, which to measure and which to hold constant (AC9S5I02), repeat each trial three times and average (repeatability and AC9S5I03 precision), then name one source of error in their own method (AC9S5I05). No new content, entirely new method, and whoever struggles here is who will struggle in Year 5.

The water cycle sits in Term 1 rather than Term 3 despite winter being when rain is most available, because the hard half of the code is evaporation and condensation, not precipitation. Precipitation is the only part students already accept. Put the unit where the gas behaviour is fastest to observe, and start a rain gauge in Term 1 so the precipitation half has real local data by the time you refer back to it.

Assessment checkpoints

One diagnostic per Understanding code, plus two for the inquiry strand.

• Biological. Give a four-organism food chain with the arrows drawn backwards and ask what is wrong with it. Naming the arrow direction means AC9S4U01 is secure. “It looks fine” means reteach by reading every arrow aloud as gives energy to. Follow up by asking what happens to the whole chain if the decomposers are removed: an answer that stops at “nothing rots” has the vocabulary but not the interactions.
• Earth and space. Point at a glass of iced water sweating and ask where the water came from. From the air means AC9S4U02 is secure. Leaked through, or came from inside, means run the two-glasses comparison again and let the dry glass make the argument.
• Physical. Roll a ball across the floor and ask what stopped it. Naming friction, and naming the surface as the thing exerting it, means AC9S4U03 is secure. “It ran out of push” or “it got tired” means the surfaces comparison needs rerunning with the same ball and the same ramp height, so that the push is visibly identical every time.
• Chemical. Ask why raincoats are not made of wool, then why oven mitts are not made of metal. Two answers that name a property and connect it to the use mean AC9S4U04 is secure. Answers about what things usually look like mean the properties were listed but never tested against a purpose.
• Inquiry, planning. Before a trial, ask in writing what will be changed, what will be measured and what will be kept the same. Three correct answers written unaided means AC9S4I02 is at Year 4 grain and Year 5 will not be a shock. Correct answers only when spoken aloud with prompting means it is still at Year 3 grain, which passes this year and will not pass next year.
• Inquiry, representation and conclusions. Give a set of measured results, not counts, and ask for a graph plus one sentence saying what it shows. A numerical axis, plus a sentence that goes beyond restating the tallest bar, means AC9S4I04 and AC9S4I05 are both secure. A graph with no conclusion sentence is the most common Year 4 outcome, and it means the conclusion step is being treated as optional: require the sentence before any result is accepted.

Records and evidence

Because eight of this year’s codes are identical to last year’s, a Year 4 portfolio that looks like the Year 3 one is a real risk, and it is the thing a reviewer will notice first. Keep evidence that shows the grain rising: a planning sheet completed in writing before the trial rather than after, a graph with a measured axis rather than a count, a scaled instrument reading taken between the markings, and one investigation repeated three times with an average. Keep the raw data sheets as well as the neat write-ups, because a sheet with three trials on it is direct evidence of the rise and a typed report is not. Caption with the code and date: “AC9S4I02 and AC9S4U03, fair test, surfaces and friction, 14 August” rather than “Science: forces”.

Our guides to which curriculum your state uses and state-by-state registration requirements cover which code set applies to you and what reviewers ask for. The equivalents elsewhere are the Victorian Levels 3 and 4 Science band, which covers this year and Year 3 in eighteen banded codes and adds fossils, gases, electrostatic force and climate that AC9 does not have here, and the NSW K–6 Science and Technology outcomes, where this content sits in Stage 2 at a noticeably coarser grain.

One practical note on Year 4 specifically. Because the inquiry codes repeat, the content is the only thing carrying novelty this year, and four unrelated topics with no shared vocabulary is a harder engagement problem than Year 3’s. The descriptor does not care what the food chain is made of or what the ball rolls across. Using an interest as the way in costs nothing: a food chain built from deep-sea animals discharges AC9S4U01 exactly as well as one built from paddock animals. Sprout Lessons builds an interactive lesson from any of these twelve codes, pitched at Year 4 and wrapped in whatever the student is currently interested in, with the AC9 code recorded in the footer. Try it free.

Australian Curriculum content descriptions are © ACARA and licensed under CC BY 4.0. Quoted here unmodified. ACARA does not endorse this product. Always verify against the current content descriptions and achievement standards at australiancurriculum.edu.au.

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