Foundation · 35 minutes · Classification
Can the same shape belong in different groups?
A sorting rule tells us which property to look at. This gate looks only at size. It does not use colour or decide which shape is nicer. When we move the gate, we change the rule, so a shape can change groups without changing itself. People decide which properties matter for a task.
Cut circles, squares and triangles in two colours and three sizes. Place two hoops or paper circles on a desk. Rehearse the browser gate; note that a size exactly on the gate goes to the large group.
Compare two objects and say which is bigger. Useful earlier investigations: none required Use pairs: one child chooses or points while the other traces or checks. Swap after one case. An adult records the child’s words; drawing and movement are equally valid evidence.
Australian Curriculum Version 9 · Digital Technologies: AC9TDIFK02. Selected aspects only. This activity contributes evidence; it does not cover the full descriptor or achievement standard. A programming descriptor is not claimed for merely moving controls. ACARA AI curriculum connection · V9 Technologies These are planning connections, not ACARA endorsement or exhaustive descriptor alignment.
Children place paper shapes in two groups. Invite two different sensible arrangements.
Ask: “Could both groups be sensible?”
Listen for: “Yes, one uses colour and one uses size.”
Show the size number of one shape and the gate. Hide its destination until a child predicts.
Ask: “Does this gate look at blue?”
Listen for: “No; it looks at how big it is.”
Move the size gate in single steps. Count each group and follow the same highlighted shape. Record a before and after drawing.
Ask: “Did the shape grow when it crossed groups?”
Listen for: “No; the gate moved.”
Use two same-size shapes of different colours, including a size exactly equal to the gate.
Ask: “Where should an equal-size shape go? How do we know?”
Listen for: “We need a rule for equal; this gate says large.”
Ask pairs to invent a sorter for envelopes that fit a small box. Choose a threshold, test three objects and revise it once.
Ask: “Which property helps with fitting in the box?”
Listen for: “Size, not colour.”
Children complete a two-picture rule poster.
Ask: “What stayed the same in your experiment?”
Listen for: “The shapes; we changed the gate.”
An object has just one correct group.
Choose one shape and draw its destination before and after moving the size gate one step.
Two equal-size shapes of different colours go to the same group. A boundary-size shape needs an explicit equality rule.
Set a size gate for a small-box sorter and test a shape on each side and exactly at the boundary.
Ask children to explain an unchanged object’s changed destination. Re-teach by physically moving a dividing string if they say the object changed size.
Use only three shapes with clearly different sizes; compare by overlaying paper shapes. Accept oral evidence.
Design a two-stage rule using size and shape. Find an object on which size-only and two-stage rules disagree.
A sorter poster with a named property and three tested shapes.
Use objects, not children, as sorting examples. Do not sort classmates by bodies, ability or personal characteristics.
Evaluate a large synthetic shape population across every possible gate; display how many destinations change at each step.
| Criterion | Beginning | Secure | Extending |
|---|---|---|---|
| Using a rule | Sorts by changing properties | Uses the size rule consistently | Explains the equality case |
| Explaining groups | Treats groups as permanent | Connects a changed group to a changed gate | Proposes another useful rule for a different task |
Australian Curriculum Version 9 · Digital Technologies
References: AC9TDIFK02. Read the current source (checked 2026-09-07).
Evidence to assess: A sorter poster with a named property and three tested shapes.
Selected aspects only. This activity contributes evidence; it does not cover the full descriptor or achievement standard. A programming descriptor is not claimed for merely moving controls. Moderate the supplied illustrative responses against your school unit and current achievement standard.
These are planning estimates to test with your class. A short session develops one supported claim; it does not compress the whole senior project.
| Stage | 45 minute focus | 60 minute investigation |
|---|---|---|
| Readiness and prediction | 0–5 | 0–5 |
| Trace the supplied example | 5–13 | 5–15 |
| Author and run cases | 13–25 | 15–35 |
| Counterexample and redesign | 25–35 | 35–45 |
| Explain and discuss | 35–42 | 45–55 |
| Export and handover | 42–45 | 55–60 |
For a longer project, use three 50-minute sessions. Session 1 (0–50): readiness, model, hypothesis and initial cases. Export a project and record the next test. Session 2 (50–100): reopen, check settings, author counterexamples and revise the design. Export the changed project and identify unresolved evidence. Session 3 (100–150): independent peer test, final artefact, individual explanation and moderation. If using two 60-minute sessions, stop at minute 60 after saving the first comparison; use 60–120 for redesign, independent test and defence.
Entry check: Compare two objects and say which is bigger. Ask the learner to demonstrate it before choosing the level of support.
Preparation: allow about 10 minutes to run the starter, print the cards and check a project can be reopened. This estimate has not yet been measured in a classroom pilot.
For young learners, show one picture or case at a time. Accept pointing, movement, a drawing or adult transcription. Read the question aloud; explain the numeric model privately to the adult. Do not assess keyboard speed or independent reading.
For one device, use a projector: one pair predicts, one operates, and the class records on paper. Swap roles after the first comparison. For individual access, support keyboard controls and a written table equivalent to each visual. Learners may explain orally or with an annotated diagram. Never require personal data, a recorded voice, or a photograph.
Mixed readiness: if the entry check is difficult, use the linked prerequisite and the first two case cards; retain the same central question. If secure, ask the learner to design an unseen test and state which explanation it could disprove.
Compare size with the gate; equality goes in the big basket. Colour is ignored.
Starting parameters: Big basket starts at = 5
4 cases calculated from your supplied inputs. Compare the evidence with your prediction.
| size | colour | basket | my prediction |
|---|---|---|---|
| 2 | green | small | small |
| 5 | orange | large | large |
| 5 | green | large | large |
| 9 | orange | large | large |
These are authored examples, not work collected from children. Assess reasoning using the lesson rubric, not whether the first prediction was correct.
Beginning: “It worked because the result looks right.” This identifies no exact case, control or measurement. Ask the learner to point to one row and say what happened.
Developing: “In the first case I recorded size: 2; colour: green; basket: small; my prediction: small.” This cites evidence, but does not yet explain how the result follows from the rule. Ask the learner to trace the relevant step.
Secure: “For the first supplied case, size: 2; colour: green; basket: small; my prediction: small. I can trace it using this mechanism: Compare size with the gate; equality goes in the big basket. Colour is ignored. My result supports a claim about these supplied cases. It does not establish that the same result holds outside them.” Look for an accurate trace, the actual settings and a bounded claim; accept equivalent oral or visual evidence.
Extending: The learner constructs and reruns a new case, reports whether the first explanation survives, and defends a revised design. Use this concrete challenge: Make two shapes the same size but different colours. Decide whether colour should change their basket. Require the original and changed evidence and this boundary: This is a chosen sorting rule, not a rule about which shapes are better.
Moderation: first assess independently against each lesson criterion. Compare the exact trace or artefact that led to your judgement. Resolve differences using evidence, not polished language. Keep each learner's individual explanation even when the artefact was produced in a group.