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What this standard actually asks for

What this standard is really grading

This standard is graded on how deeply you understand the physics, not on how well you describe the context. The wording of the three criteria tells you exactly what is being looked for.

Grade	The standard's wording	What that means you write
Achieved	Provide characteristics of, or an account of, the physics related to the context	Correctly describe the relevant physics concepts, using the right terms
Merit	Provide reasons as to how or why the physics applies to the context	Explain the mechanism — why this concept produces this effect here
Excellence	Link ideas to integrate the physics, and elaborate, justify, relate, evaluate, compare and contrast, or analyse	Connect two or more concepts into one explanation, and use them to justify or evaluate something specific

The single most important rule

The marks are for the physics, not for the context. A beautifully written description of how an airbag is manufactured earns nothing; a short paragraph explaining how it increases the time of impact and therefore reduces the force earns Merit.
Ask of every sentence you write: which physics concept is this sentence about? If the honest answer is "none", it is background, not evidence.

What counts as evidence

Explanations in your own words, using correct physics terminology.
Calculations using the physics of the context, with realistic values.
Diagrams — force diagrams, ray diagrams, circuit diagrams, energy-flow diagrams — properly labelled.
Your own measurements and observations, where the context allows them (timing a swing, measuring a temperature drop, reading a power rating off an appliance).
Not evidence: copied text, or a paraphrase that changes the words but shows no sign that you understood them.

Choosing which physics to include

Include physics that genuinely explains a feature of the context.
Leave out physics that is correct but irrelevant. A definition of momentum in a report on lens design does not earn credit, and it dilutes the report.
Two or three concepts explained thoroughly beats six concepts mentioned.

From Achieved to Excellence, on one idea

Take a bicycle helmet as the example.

Achieved (describe): "A helmet contains a layer of polystyrene foam, which is crushable. Impulse is the product of force and the time over which it acts, $J = Ft$ ."
Merit (reasons how or why): "The foam crushes during an impact, so the head takes longer to come to rest. The change in momentum is fixed by the speed the head was travelling at, and since $Ft = \Delta p$ , spreading the same change in momentum over a longer time means the force on the skull is smaller."
Excellence (integrate and justify): links impulse–momentum with energy: "...the foam also does work as it crushes, converting the head's kinetic energy into deformation of the foam. This is why the foam must be permanently crushable rather than springy: a springy material would return the energy and push the head back, whereas a crushable one absorbs it. Both ideas point to the same design rule and explain why a helmet that has taken one impact must be replaced even if it looks intact."

Tips and Tricks

The commonest way to lose marks on this standard is to describe what the technology does rather than the physics that makes it work. If you could write your sentence without knowing any physics at all, it is not going to be credited — go back and name a concept, a relationship, or a formula.

Apply the "so what?" test to every sentence you write. State a fact, then ask "so what does that explain?" If the next sentence answers it with physics, you are writing at Merit. If it answers it by connecting to a second concept, you are writing at Excellence. If there is no answer, delete the sentence.

Quote the relationships you use, even in a written report. A report that says "the force is reduced because the time is longer" is Merit; the same sentence with $F = \Delta p / t$ beside it, and the symbols explained, is stronger evidence of understanding and costs one line.

Worked ExampleRewriting a weak paragraph up the grade ladder

A student writing about car braking systems submits this paragraph:

"Cars have anti-lock braking systems (ABS). ABS stops the wheels locking up when you brake hard. This helps the car stop safely and lets the driver steer. Modern cars all have ABS and it is much safer than older systems."

Assess this paragraph and rewrite it to reach Excellence.

Step 1 — Assess what is there

The paragraph is accurate and clearly written, but it contains no physics at all. Every sentence describes what the technology does; none explains why it works. A person with no physics knowledge could have written it from a car advertisement.

As it stands it would earn no credit — not even Achieved, which requires physics concepts to be described, not just the technology.

Step 2 — Add physics concepts (reaches Achieved)

Name the relevant physics and define it:

Physics is now present and correct — Achieved.

Step 3 — Give reasons why (reaches Merit)

Explain how the physics produces the observed behaviour:

The physics now explains the technology — Merit.

Step 4 — Connect concepts and justify (reaches Excellence)

Bring in a second concept and use both together:

"Steering control is lost under lock-up for a related but separate reason. A sliding tyre can only exert friction opposite to its direction of sliding, so no sideways force is available — and a sideways force is exactly what is needed to provide the centripetal force, $F_c = mv^2/r$ , that turns the car. Without it the car cannot follow a curved path and continues in a straight line along its original direction, as Newton's first law requires, no matter how the wheel is turned.

By preventing lock-up, ABS keeps the tyres rolling, which preserves both the larger braking friction and the ability to generate a sideways centripetal force. This is why ABS improves stopping distance and steerability through the same mechanism, and it explains the counter-intuitive advice to brake hard and steer at the same time in an ABS-equipped car — advice that would be dangerous in a car without it."

Two concepts — friction and circular motion — are now integrated to explain a single feature, and the explanation is used to justify a real-world consequence. This is Excellence.

$\text{No physics} \to \text{concepts} \to \text{reasons} \to \text{connected concepts}$

What this standard actually asks for

Covers AS91169

What this standard is really grading

This standard is graded on how deeply you understand the physics, not on how well you describe the context. The wording of the three criteria tells you exactly what is being looked for.

Grade	The standard's wording	What that means you write
Achieved	Provide characteristics of, or an account of, the physics related to the context	Correctly describe the relevant physics concepts, using the right terms
Merit	Provide reasons as to how or why the physics applies to the context	Explain the mechanism — why this concept produces this effect here
Excellence	Link ideas to integrate the physics, and elaborate, justify, relate, evaluate, compare and contrast, or analyse	Connect two or more concepts into one explanation, and use them to justify or evaluate something specific

The single most important rule

The marks are for the physics, not for the context. A beautifully written description of how an airbag is manufactured earns nothing; a short paragraph explaining how it increases the time of impact and therefore reduces the force earns Merit.
Ask of every sentence you write: which physics concept is this sentence about? If the honest answer is "none", it is background, not evidence.

What counts as evidence

Explanations in your own words, using correct physics terminology.
Calculations using the physics of the context, with realistic values.
Diagrams — force diagrams, ray diagrams, circuit diagrams, energy-flow diagrams — properly labelled.
Your own measurements and observations, where the context allows them (timing a swing, measuring a temperature drop, reading a power rating off an appliance).
Not evidence: copied text, or a paraphrase that changes the words but shows no sign that you understood them.

Choosing which physics to include

Include physics that genuinely explains a feature of the context.
Leave out physics that is correct but irrelevant. A definition of momentum in a report on lens design does not earn credit, and it dilutes the report.
Two or three concepts explained thoroughly beats six concepts mentioned.

From Achieved to Excellence, on one idea

Take a bicycle helmet as the example.

Achieved (describe): "A helmet contains a layer of polystyrene foam, which is crushable. Impulse is the product of force and the time over which it acts, $J = Ft$ ."
Merit (reasons how or why): "The foam crushes during an impact, so the head takes longer to come to rest. The change in momentum is fixed by the speed the head was travelling at, and since $Ft = \Delta p$ , spreading the same change in momentum over a longer time means the force on the skull is smaller."
Excellence (integrate and justify): links impulse–momentum with energy: "...the foam also does work as it crushes, converting the head's kinetic energy into deformation of the foam. This is why the foam must be permanently crushable rather than springy: a springy material would return the energy and push the head back, whereas a crushable one absorbs it. Both ideas point to the same design rule and explain why a helmet that has taken one impact must be replaced even if it looks intact."

Tips and Tricks

Worked ExampleRewriting a weak paragraph up the grade ladder

A student writing about car braking systems submits this paragraph:

"Cars have anti-lock braking systems (ABS). ABS stops the wheels locking up when you brake hard. This helps the car stop safely and lets the driver steer. Modern cars all have ABS and it is much safer than older systems."

Assess this paragraph and rewrite it to reach Excellence.

Step 1 — Assess what is there

As it stands it would earn no credit — not even Achieved, which requires physics concepts to be described, not just the technology.

Step 2 — Add physics concepts (reaches Achieved)

Name the relevant physics and define it:

Physics is now present and correct — Achieved.

Step 3 — Give reasons why (reaches Merit)

Explain how the physics produces the observed behaviour:

The physics now explains the technology — Merit.

Step 4 — Connect concepts and justify (reaches Excellence)

Bring in a second concept and use both together:

Two concepts — friction and circular motion — are now integrated to explain a single feature, and the explanation is used to justify a real-world consequence. This is Excellence.

$\text{No physics} \to \text{concepts} \to \text{reasons} \to \text{connected concepts}$