Year 2 · 45 minutes · Training data
Is a bigger collection always a better collection?
Examples help only with what they show. A collector who stays in the middle of a habitat can gather many copies and still miss creatures at the edges. Our coverage model checks whether each test creature has a nearby training example. Coverage is not the same as accuracy: being near an example does not prove its label is correct.
Scatter 12 paper creatures across a habitat strip, including two at each end. Cut a movable collection window. Rehearse the fixed test positions and explain that the coverage radius is a teaching choice.
Count examples inside and outside a drawn boundary. Useful earlier investigations: f-sort 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: AC9TDI2K02, AC9TDI2P03. 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.
Take several copies of the central creature. Count them beside a smaller varied collection.
Ask: “Which collection tells us about the edge?”
Listen for: “The one with creatures from different places.”
Predict how copying central examples changes the number of covered test creatures.
Ask: “Will an extra copy move an example closer to the edge?”
Listen for: “No, it stays in the middle.”
Change window width with the habitat and coverage radius fixed. Inspect covered test positions and gaps; record counts.
Ask: “Which test creature became covered first?”
Listen for: “The one just outside the old window.”
Increase duplicate copies without widening the window and compare coverage.
Ask: “The collection grew. What did not improve?”
Listen for: “The uncovered edges stayed uncovered.”
Choose a wider or shifted window that covers both extremes. Draw a sampling plan and identify one remaining gap.
Ask: “How would you collect differently next time?”
Listen for: “Go to the places we have not sampled.”
Present count and coverage as separate measures.
Ask: “Does covered mean certain to be right?”
Listen for: “No, the nearby example may still have the wrong label.”
More copies mean better learning.
Double the copies of central examples. Predict whether edge coverage changes before checking.
Many duplicates increase sample count but leave the nearest-example distances at habitat edges unchanged.
Improve coverage by changing where examples are collected while keeping all test positions fixed.
Check that a student can point to a gap and distinguish a larger count from a wider spread. Ask them to predict one new collection position.
Use six large test positions and coloured strings to show a nearby-example radius.
Fix the collection budget at four examples; spread them to minimise the largest uncovered gap.
A before/after habitat coverage map and a justified collection plan.
All data are synthetic. A real habitat survey would require teacher supervision and environmental permissions; the browser requires no field collection.
Compare thousands of random and stratified sampling plans against a fixed synthetic habitat; display coverage distributions rather than a single lucky sample.
| Criterion | Beginning | Secure | Extending |
|---|---|---|---|
| Sampling reasoning | Equates more with better | Distinguishes duplicates from variety | Explains a specific coverage gap |
| Collection redesign | Adds arbitrary copies | Adds examples near uncovered tests | Justifies coverage gains and remaining limitations |
Australian Curriculum Version 9 · Digital Technologies
References: AC9TDI2K02, AC9TDI2P03. Read the current source (checked 2026-09-07).
Evidence to assess: A before/after habitat coverage map and a justified collection plan.
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: Count examples inside and outside a drawn boundary. 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.
A location is covered if any collected example is within the selected distance.
Starting parameters: Near enough = 1.5
4/6 positions covered by 3 distinct collected positions.
| position | covered |
|---|---|
| 1 | True |
| 2 | True |
| 4 | False |
| 6 | False |
| 8 | True |
| 9 | True |
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 position: 1; covered: True.” 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, position: 1; covered: True. I can trace it using this mechanism: A location is covered if any collected example is within the selected distance. 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: Choose two collecting places with the same collection budget. Explain what each misses. Require the original and changed evidence and this boundary: Coverage is proximity in one made-up feature; copying an example adds no new position.
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.