# Day 36 · What would make the comparison fair?

**Start:** “Pick one thing to change. What needs to stay the same?”

**Purpose:** Plan a scaffolded comparison, make an observation-based prediction and learn familiar volume/duration scale procedures.

## Prepare

Read today's complete model and two contexts before the session. Paper, a pencil and the full written picture words are sufficient. Optional actual water work follows [ordinary preparation](../teacher/PREPARATION.html); the teacher chooses suitable familiar materials/instruments. Use today's three routes without assigning a fixed learning-style label.

## Run the session

1. Reconnect: discuss the supported explanation for a smaller puddle, plus other paths that could reduce visible water.

2. Model: two matched trays begin with 40 mL clean water in the same room for the same 20 minutes. Only one gets a cover. The planning question is whether remaining amounts differ; do not promise a measurable effect within twenty minutes.

3. Try: practise the paper scale 0/10/20/30/40 mL and a reading at exactly 20 mL. With a familiar available instrument, teacher explicitly teaches actual safe scale-reading/recording before observed child use. A practice picture is not that conduct.

4. Compare: sort change / keep / measure: cover; start volume, tray, place and duration; amount remaining. A spill or changed location can undermine the comparison. Predict cautiously from earlier supplied clues, not from a tool-created answer.

5. Make: fill the scaffold: question; observation behind prediction; one change; matched conditions; safe steps; instrument/unit; record time and result. Optional actual run starts only under suitable teacher-managed conditions; otherwise keep it a plan.

6. Exit: “My comparison changes __ and keeps __ the same. I would record __ in __.” Teacher records whether the child actually used the instrument and followed steps.

## Three ways in

### Plan builder

Select one-change/matched-condition cards and a mL recording header; use dictated wording for the complete plan.

**Worked ordinary reasoning:** Change the cover; match trays, start volume, room and 20-minute duration; measure remaining mL with the taught procedure.

### Scale station

First interpret the explicit paper scale, then optionally use the site's familiar scaled container with teacher observation and usual access support.

**Worked ordinary reasoning:** The drawn 20 mL mark is a supplied reading. Actual use is recorded only if it happened, with the actual value/support.

### Fair-test repair

Review a supplied unfair plan: one tray starts 40 mL, the other 20 mL and is moved outside. Edit two mismatches before choosing a prediction.

**Worked ordinary reasoning:** Match starting volume and place before comparing covers; we cannot conclude a cover effect from this unfair plan.

## Look and choose the next teaching

Complete feasible scaffold and matched conditions; actual measurement evidence stays separate.

For unit/increment confusion teach a new clear 10 mL scale first; never mark an invented real measurement.

## Today's complete resources

[A10 · whole labelled picture](../aids/A10.svg) · [A10 · complete picture words](../aids/A10-alternative.html)

[A11 · whole labelled picture](../aids/A11.svg) · [A11 · complete picture words](../aids/A11-alternative.html)

[C11](../contexts/C11.html)

[C12](../contexts/C12.html)

[H06](../home/H06.html)

[X06](../projects/X06.html)

[Short child start](../child/day-36.html) · [Written read-aloud](../narration/day-36.html) · [Water Trail and paper](../interactive/index.html)

Partial opportunities: AC9S4I01, AC9S4I02, AC9S4I03, AC9S4H01 · [Full mapping and limits](../teacher/CURRICULUM.html)

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<summary>Grown-up help</summary>

Allow source access and neutral reading/support. Keep supplied story, child response, helper actions and actual observation distinct. Use component-specific criteria after the response, not a model answer before it. Suggested six-move timing 4/7/12/8/6/3 minutes may be split; there is no performance timer.

Modified from [Year 4 Science alignment](https://www.qcaa.qld.edu.au/downloads/aciqv9/science/curriculum/ac9_science_yr4_as_cd_alignment.pdf), [standard elaborations](https://www.qcaa.qld.edu.au/downloads/aciqv9/science/assessment/ac9_science_se_yr4.pdf) and [Years 3–4 techniques and conditions](https://www.qcaa.qld.edu.au/downloads/aciqv9/science/assessment/ac9_science_tc_yr3-4.pdf), © State of Queensland ([QCAA](https://www.qcaa.qld.edu.au/copyright)) 2023, covered [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) with exceptions. Our task criteria are original; these are not official A–E bands. Actual folio and on-balance professional judgment remain necessary.

</details>