Hold up a clear cup of water and a spoon of sugar (or salt). Do not tip it in yet. Ask: Where do you think the sugar goes when we stir it in tea? Take three or four quick ideas. Do not correct them yet.

Keep the hook light: no apparatus layout, no variables list, no vocabulary table. The trays come out in the plan and investigate steps.

Link to everyday life: people in Irish kitchens dissolve salt when cooking and sugar in tea every day. Scientists use the same idea when they make medicines that mix into water.

Board pace: put the question and four materials up first. Say the short dissolve line once. Move straight to partner predictions. Do not dump solution or fair test on the IWB here; name them lightly if a child uses the idea, then unpack fair test with the cards in the next step and solution when results are clear.

Misconception to head off: children often say dissolving means the solid has "disappeared" or been destroyed. Keep saying: it is still there, mixed into the water. Flour is a common trap: it makes the water cloudy but does not truly dissolve; fine bits stay suspended and may settle.

Worked model (say aloud before groups test — question, prediction and method only; do not give the sugar result or the solution conclusion yet): I wonder which materials will dissolve. I predict sugar will dissolve because I have seen it in tea. I will put one level spoon of sugar into this cup of water, stir twenty times the same way, and look carefully. Then I will record what I see.

Save the observed result and the solution line for the live sugar model in step 4 and the evidence talk in step 6.

Take a quick class vote of predictions for sugar, salt, sand and flour. Predictions are never wrong; they start the science.

Before the Lesson

• Open the fair-test-planner interactive on the IWB in explore mode.
• Have group trays ready but keep them to one side until the experiment step.
• Print the Investigation Journal page (one per pupil).

Driving the interactive

Six cards appear on screen: the material, does it dissolve? how fast?, amount of water, spoonful of solid, how we stir, and the cup. Read each card aloud as it appears rather than listing them all in one breath on the board.

• Drag the material to Change.
• Drag does it dissolve? how fast? to Measure.
• Drag amount of water, spoonful of solid, how we stir and the cup to Keep the same.

Narrate each keep-the-same card: If one cup got more water, or a heaped spoon, or more stirring, we would not know whether the material or our method made the difference.

Say aloud that the teacher pours the same warm water for every cup, so water temperature stays the same without needing its own card. Amount of water and teacher-poured water already cover sameness.

Ask: What would make this test unfair? (different water amounts, different spoon sizes, tasting, tipping cups).

Land the phrase fair test here with the cards: change one thing, measure one thing, keep the rest the same.

Do not read out a model prediction that names which materials will dissolve. Collect the class vote from step 2, or invite one pupil stem such as "I think sugar will…", then leave outcomes for the test.

Differentiation: less confident groups call out which bin; more confident pupils justify why a card cannot go in Change.

Staging the 20 minutes

1. Minutes 0–3: Send trays out by table (cups empty and pre-marked with a fill line if you can, labelled pots, spoons, towels, journals ready). Groups set cups in a row and check labels while you still hold the jug.
2. Minutes 3–6: Model once with sugar at the front: level spoon, twenty slow stirs, look for clear water or bits left. Agree the timing words on the board: quick / a while / not at all. After the live look, say briefly what you saw (for example clear water, pieces gone) so groups know what to watch for — leave the full solution talk for step 6.
3. Minutes 6–10: Batch-pour warm water table by table to the same fill line. Do not wait for every group to finish labelling before the first pour; keep the jug moving.
4. Minutes 10–18: Groups run sugar, salt, sand, flour in turn. After each cup they jot a quick tick or timing word on the journal. Circulate for fair spoonfuls, calm stirring and no tasting.
5. Minutes 18–20: Cups sit still; whole-class glance: clear, grains on the bottom, or cloudy?

Pour capacity (pick what matches your class)

One teacher with one jug is tight for a full 3rd Class. Use at least one of these levers without changing the fair-test design:

• A second jug (and a second adult or SNA if available) so two tables are poured at once.
• Cups pre-marked with a fill line the night before so each pour is a quick match-to-the-line.
• Half the class tests first while the other half watches and predicts, then swap (same method, fewer simultaneous pours).
• Pre-pour to the fill line on a side table just before this step if water will stay warm enough for a few minutes.

Teacher-poured water from the same source still keeps temperature and amount the same for every cup in a group's set.

Setup

One tray per group of about four: four identical clear cups, four labelled pots or piles (sugar, salt, clean play sand, plain flour), four spoons or one shared spoon wiped between materials, paper towels, Investigation Journal pages. You pour the warm water (hand-safe warm from a kettle left to cool, or warm tap water). Same fill line on every cup.

Method to model once with sugar

1. Pour warm water to the same mark in each cup.
2. Add one level spoon of the material.
3. Stir twenty slow times (same count every cup).
4. Look: have the solid pieces gone? Is the water clear or cloudy? Has anything settled on the bottom?
5. Record time as quick / a while / not at all (no stopwatch needed; optional classroom clock only if you prefer).
6. Jot a quick note, then move to the next material.

What to expect

• Sugar: dissolves; water stays clear or slightly shiny.
• Salt: dissolves; may take a little longer than sugar; water stays clear.
• Sand: does not dissolve; grains stay visible and sink.
• Flour: water goes cloudy; flour does not truly dissolve (suspension). Bits may settle if left still. Name this gently: cloudy is not the same as dissolved.

If sugar seems slow: water may be too cool, or the spoon was heaped. Keep calm, rematch the keep-the-sames, try one more level spoon in a fresh cup.

Safety while circulating: no tasting; wipe spills at once; flour can puff — tip gently; stop anyone stirring wildly near faces.

Fold the whole class in: when one group reports, ask the watchers Do you agree? What did your sand do?

Pupils use the Investigation Journal page. Put the I saw / I think example on the board and leave it up while they write. Prompt them to complete sugar, salt, sand and flour from their quick jots: dissolves or not, quick / a while / not at all, and a short observation note.

Look-fors:

• Sugar and salt marked as dissolving.
• Sand marked as not dissolving, with grains still visible.
• Flour noted as cloudy or not truly dissolved rather than "dissolved like sugar".
• Observation language ("I saw grains on the bottom") kept separate from inference ("so sand does not dissolve").

If a group's sugar did not dissolve, help them check the keep-the-sames rather than forcing the "right" answer onto the page. Unexpected results are still data.

Early finishers: sketch one cup before and after stirring, or write one sentence about which result surprised them (still on the journal page, not a new sheet).