Australian Curriculum v9 / ACiQ Year 10 Science - Unit 4 - Investigable questions, hypotheses and explanatory models

Investigable questions, hypotheses and explanatory models

Develop focused questions and hypotheses derived from scientific models with measurable variables and plausible mechanisms.

Updated 2026-07-26 - 12 min read

Investigable questions, hypotheses and explanatory models is taught here as a connected set of decisions, not a list of facts. Work through the prerequisite recall, explicit models, carefully faded examples, misconception repairs and transfer task before using the target in Check, Practice, Review or Rapid Revision.

This note is designed to work with the guided lessons, curated practice, flashcards, Tutor context, Review and Rapid Revision for the same canonical target. The same three evidence checks are used throughout, so feedback can route a learner back to the precise idea that needs repair.

Derive an investigable question

A strong question operationalises variables, population or system, range and measurable outcome. Use the model to make a prediction, connect it to observable evidence and state any relevant condition or limitation.

A dependable reasoning routine

  1. Define the system or phenomenon and identify the change being explained.
  2. Trace the mechanism for derive an investigable question in causal order rather than listing disconnected terms.
  3. Link each claim to an observation, measurement, model or accepted scientific relationship.
  4. State the boundary of the conclusion: what was tested, what remains uncertain and what evidence would strengthen it.

Repair: Scope the question to a feasible relationship.

The repair matters because the shortcut may appear to work in one familiar example while failing when the system boundary, causal mechanism, variable or evidence limit changes. Use the routine above to make the reasoning visible enough for another learner to verify.

Example 1.1

Which statement correctly explains derive an investigable question?

Step 1 - identify the governing idea: A strong question operationalises variables, population or system, range and measurable outcome.

Step 2 - apply it to this evidence: It states the governing scientific relationship and its conditions.

Result: A strong question operationalises variables, population or system, range and measurable outcome.

The evidence-to-mechanism link is: It states the governing scientific relationship and its conditions. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • Any broad why-question is directly testable. — It conflicts with the stated mechanism or evidence: It states the governing scientific relationship and its conditions.
  • A single observation proves the claim in every context. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • The scientific terms can be rearranged without changing the mechanism. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 1.2

A student says: "Any broad why-question is directly testable." What is the best correction?

Step 1 - identify the governing idea: A strong question operationalises variables, population or system, range and measurable outcome.

Step 2 - apply it to this evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.

Result: Scope the question to a feasible relationship.

The evidence-to-mechanism link is: The correction identifies the precise conceptual error and replaces it with a testable explanation. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • Repeat the claim with more technical vocabulary. — It conflicts with the stated mechanism or evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.
  • Ignore conflicting evidence. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • Treat the model as a literal picture with no limits. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 1.3

Improve 'Does temperature affect reactions?'

Step 1 - identify the governing idea: A strong question operationalises variables, population or system, range and measurable outcome.

Step 2 - apply it to this evidence: Variables, range and measure are explicit.

Result: How does 20–60°C affect initial reaction rate measured by gas volume per minute?

The evidence-to-mechanism link is: Variables, range and measure are explicit. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • A conclusion that ignores the named mechanism — It conflicts with the stated mechanism or evidence: Variables, range and measure are explicit.
  • An answer based on one familiar keyword — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • A claim that exceeds the available evidence — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Model-based hypothesis

A hypothesis predicts direction and explains it using a scientific mechanism. Use the model to make a prediction, connect it to observable evidence and state any relevant condition or limitation.

A dependable reasoning routine

  1. Define the system or phenomenon and identify the change being explained.
  2. Trace the mechanism for model-based hypothesis in causal order rather than listing disconnected terms.
  3. Link each claim to an observation, measurement, model or accepted scientific relationship.
  4. State the boundary of the conclusion: what was tested, what remains uncertain and what evidence would strengthen it.

Repair: The rationale makes the prediction scientifically testable.

The repair matters because the shortcut may appear to work in one familiar example while failing when the system boundary, causal mechanism, variable or evidence limit changes. Use the routine above to make the reasoning visible enough for another learner to verify.

Example 2.1

Which statement correctly explains model-based hypothesis?

Step 1 - identify the governing idea: A hypothesis predicts direction and explains it using a scientific mechanism.

Step 2 - apply it to this evidence: It states the governing scientific relationship and its conditions.

Result: A hypothesis predicts direction and explains it using a scientific mechanism.

The evidence-to-mechanism link is: It states the governing scientific relationship and its conditions. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • A hypothesis is a prediction with no because clause. — It conflicts with the stated mechanism or evidence: It states the governing scientific relationship and its conditions.
  • A single observation proves the claim in every context. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • The scientific terms can be rearranged without changing the mechanism. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 2.2

A student says: "A hypothesis is a prediction with no because clause." What is the best correction?

Step 1 - identify the governing idea: A hypothesis predicts direction and explains it using a scientific mechanism.

Step 2 - apply it to this evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.

Result: The rationale makes the prediction scientifically testable.

The evidence-to-mechanism link is: The correction identifies the precise conceptual error and replaces it with a testable explanation. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • Repeat the claim with more technical vocabulary. — It conflicts with the stated mechanism or evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.
  • Ignore conflicting evidence. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • Treat the model as a literal picture with no limits. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 2.3

Best rate hypothesis for temperature?

Step 1 - identify the governing idea: A hypothesis predicts direction and explains it using a scientific mechanism.

Step 2 - apply it to this evidence: Collision theory supplies the mechanism.

Result: Rate will rise because a larger fraction of collisions exceed activation energy

The evidence-to-mechanism link is: Collision theory supplies the mechanism. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • A conclusion that ignores the named mechanism — It conflicts with the stated mechanism or evidence: Collision theory supplies the mechanism.
  • An answer based on one familiar keyword — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • A claim that exceeds the available evidence — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Testing explanatory models

Design observations that discriminate between model predictions and state the model's domain and assumptions. Use the model to make a prediction, connect it to observable evidence and state any relevant condition or limitation.

A dependable reasoning routine

  1. Define the system or phenomenon and identify the change being explained.
  2. Trace the mechanism for testing explanatory models in causal order rather than listing disconnected terms.
  3. Link each claim to an observation, measurement, model or accepted scientific relationship.
  4. State the boundary of the conclusion: what was tested, what remains uncertain and what evidence would strengthen it.

Repair: Competing explanations require discriminating evidence.

The repair matters because the shortcut may appear to work in one familiar example while failing when the system boundary, causal mechanism, variable or evidence limit changes. Use the routine above to make the reasoning visible enough for another learner to verify.

Example 3.1

Which statement correctly explains testing explanatory models?

Step 1 - identify the governing idea: Design observations that discriminate between model predictions and state the model's domain and assumptions.

Step 2 - apply it to this evidence: It states the governing scientific relationship and its conditions.

Result: Design observations that discriminate between model predictions and state the model's domain and assumptions.

The evidence-to-mechanism link is: It states the governing scientific relationship and its conditions. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • A model that fits one result is proven. — It conflicts with the stated mechanism or evidence: It states the governing scientific relationship and its conditions.
  • A single observation proves the claim in every context. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • The scientific terms can be rearranged without changing the mechanism. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 3.2

A student says: "A model that fits one result is proven." What is the best correction?

Step 1 - identify the governing idea: Design observations that discriminate between model predictions and state the model's domain and assumptions.

Step 2 - apply it to this evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.

Result: Competing explanations require discriminating evidence.

The evidence-to-mechanism link is: The correction identifies the precise conceptual error and replaces it with a testable explanation. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • Repeat the claim with more technical vocabulary. — It conflicts with the stated mechanism or evidence: The correction identifies the precise conceptual error and replaces it with a testable explanation.
  • Ignore conflicting evidence. — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • Treat the model as a literal picture with no limits. — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Example 3.3

Two models predict different results only at high concentration. Best test?

Step 1 - identify the governing idea: Design observations that discriminate between model predictions and state the model's domain and assumptions.

Step 2 - apply it to this evidence: The design targets where predictions diverge.

Result: Measure within that high-concentration range while controlling other variables

The evidence-to-mechanism link is: The design targets where predictions diverge. Notice that the conclusion does not extend beyond the stated system or evidence. A scientific explanation must trace cause and effect, not only name the relevant vocabulary.

Why the alternatives fail:

  • A conclusion that ignores the named mechanism — It conflicts with the stated mechanism or evidence: The design targets where predictions diverge.
  • An answer based on one familiar keyword — It changes the system boundary or claims a cause that the supplied observations do not establish.
  • A claim that exceeds the available evidence — It extends the conclusion beyond the evidence. A valid answer must preserve the variables, sequence and uncertainty in the prompt.

Retrieval check

Try these without looking back at the examples.

  1. A student says: "Any broad why-question is directly testable." What is the best correction?
  2. A student says: "A hypothesis is a prediction with no because clause." What is the best correction?
  3. A student says: "A model that fits one result is proven." What is the best correction?

Answers

  1. Scope the question to a feasible relationship. — The correction identifies the precise conceptual error and replaces it with a testable explanation.
  2. The rationale makes the prediction scientifically testable. — The correction identifies the precise conceptual error and replaces it with a testable explanation.
  3. Competing explanations require discriminating evidence. — The correction identifies the precise conceptual error and replaces it with a testable explanation.

Transfer task

Find an unfamiliar example from school, daily life, a credible news source or another subject. Explain which of the three evidence checks applies. Complete the task, then audit your own response: identify the evidence used, the relationship applied, one plausible misconception and the final reasonableness check. If a peer could not reproduce your reasoning, add the missing step.

Sources