Offline Classroom Activities — Science 7
Term 1 · Week 4 · CG Quarter 1, competency 5 · Changes of state and the particle model
Three individual and two group activities. No electricity, nothing to buy, no laboratory equipment, and nothing heated. All five are written for a room of 45 or more with fixed desks.
Two of these use the class as the particles. A model of something too small to see is unusually well served by bodies in a room: the arrangement, the spacing and the motion are all real, and nobody can accidentally draw themselves bigger.
Activity 1 — Be the Particles (group)
| Time | 30 minutes |
| Group size | 6 — works at 5 to 8 |
| Materials | Floor space. A corridor, the covered court, or the front of the room with desks pushed back |
| Preparation | Five minutes: mark a rectangle on the floor with chalk or with four bags. That rectangle is the container and it does not move. |
Roles — everybody has one
| Role | What they do | How many |
|---|---|---|
| Caller | Announces the state, and then the change. Nobody moves until the Caller has said which change | 1 |
| Energy Keeper | Says whether energy is going in or out for each change, before it happens | 1 |
| Spacing Judge | After each change, says whether the group is closer together or further apart than before | 1 |
| Recorder | Writes the state, the energy direction and the spacing for all four changes | 1 |
| Particles | Everyone else. They must obey the rules below exactly | 2+ |
The Caller, the Energy Keeper and the Spacing Judge are also particles — they move too. Nobody stands out of the rectangle.
The rules the particles obey
| State | Arrangement | Spacing | Motion |
|---|---|---|---|
| Solid | A neat grid | Shoulders touching | Rock gently on the spot. Feet do not move |
| Liquid | No pattern | Still touching or nearly | Slide past each other, slowly, staying in contact |
| Gas | No pattern | Spread to the whole rectangle | Walk briskly in straight lines, change direction only on contact |
Instructions
- Start as a solid. Hold it for thirty seconds.
- The Caller says melting. The Energy Keeper says energy in before anybody moves.
- Become a liquid. The Spacing Judge reports.
- The Caller says boiling. Same procedure.
- Then condensing, then freezing, back down.
- The Recorder reads back all four rows. The group checks them.
The three rules nobody may break
- Nobody may leave the rectangle. The container is the container. Matter is conserved.
- Nobody may grow. No arms out to look bigger in the gas phase. The particles do not swell.
- Nobody may stop. Even in the solid, the rocking continues. Particles never stop moving.
Say all three before starting, and enforce them lightly and consistently. They are the three denials in physical form, and a learner who has been told off for spreading their arms in the gas phase does not later draw bigger circles.
Rubric — 12 marks
| Criterion | 3 | 2 | 1 | 0 |
|---|---|---|---|---|
| All four changes performed | Four, each distinct from the last | Three | Two | One |
| Energy called before the move | Every time, and correct every time | Correct most times | Called after the move | Not called |
| The three rules held | Nobody left, grew or stopped | One lapse | Several lapses | Rules ignored |
| The record | All four rows, complete and correct | Three rows | One or two | Nothing written |
Activity 2 — The Regress (group)
| Time | 20 minutes |
| Group size | The whole class, standing |
| Materials | None |
| Preparation | None. Best run on Day 3, immediately after somebody says air. |
Instructions
- Six learners stand as the particles of a liquid — close together, no pattern.
- Ask the class: "What is in the gaps between them?" Somebody will say air.
- Ask four more learners to stand in the gaps. "These are the air particles."
- Now ask: "What is in the gaps between the air particles?"
- Send more learners in. Keep going.
- Stop when the class runs out of learners, or out of floor, or out of patience — whichever comes first.
The conversation at the end
Ask: "When does this stop?"
It does not. Every answer of air creates new gaps that need a new answer. The only answer that ends the regress is nothing.
Then say the harder half: "That is uncomfortable, and it should be. Nothing is not a thing. But the model says the spaces are empty, and the model is right — the alternative goes on forever."
Why this cannot be delivered as a sentence
Every learner has been told that there is nothing between particles, and most of them have nodded and continued to picture air. The regress has to be walked into, and it takes twenty minutes of increasingly crowded floor to be felt rather than agreed with.
Rubric — 12 marks
| Criterion | 3 | 2 | 1 | 0 |
|---|---|---|---|---|
| The class reached the regress | Somebody said "this never stops" unprompted | Reached it when asked | The teacher stated it | Not reached |
| The conclusion is stated | Nothing — said by a learner, in their own words | Stated by a learner when prompted | Stated by the teacher | Not stated |
| Written afterwards | Every learner writes the regress in two sentences | Most do | Some do | Not written |
| Everybody stood in | The whole class took part | Most | Half | A demonstration watched by the rest |
Activity 3 — Three Observations, One Model (individual)
| Time | 25 minutes |
| Materials | A cold surface — a metal spoon kept in shade, a tile, a bottle from a cool place; chalk; the concrete outside |
| Preparation | Ten minutes: put a bottle of water somewhere cool an hour before the lesson. |
The three observations
| Observation | How to get it | What the model has to explain |
|---|---|---|
| Breath on a cold surface | Breathe on the spoon or the bottle | Water vapour in warm breath condenses when it loses energy |
| A puddle on the concrete | Draw round a small puddle with chalk in the morning; look at it after lunch | The fastest particles at the surface escape, at any temperature |
| A wet hand, fanned | Wet the back of a hand and fan it | The fastest particles leave, so what stays behind has less energy — it is cooler |
Instructions
- Do all three. Write down what you saw, in one sentence each, before explaining anything.
- Then write what the model says is happening, one sentence each.
- Underline the words particle, energy and spacing wherever they appear in your second column.
- Answer: which of the three would be impossible if the particle model were wrong?
Why step 4 is the whole activity
A model that explains three things after the fact is doing bookkeeping. A model that says something would be impossible is making a claim. Fanning a wet hand is the strongest of the three, because nothing in everyday language predicts that removing water makes something colder.
Differentiation
| One step down | One observation — the wet hand — with the two columns and no step 4. |
| One step up | Find a fourth observation nobody in the class has used, and write both columns for it. |
Assessment
Read the second column. Count how many sentences mention energy moving. A learner who writes "the water dried" has described, not explained; a learner who writes "the fastest particles took energy with them" has used the model.
Activity 4 — Draw It, Break It (individual)
| Time | 20 minutes |
| Materials | Paper; a coin to trace |
| Preparation | Five minutes: draw the four flawed diagrams on the board, or copy them onto a sheet. |
The four flawed diagrams
| # | The drawing | What is wrong |
|---|---|---|
| 1 | Steam with bigger circles than ice, far apart | Particles do not swell |
| 2 | A liquid with tiny dots labelled 'air' in the gaps | There is nothing in the gaps |
| 3 | A solid drawn as a neat grid, labelled "particles do not move" | They vibrate in place |
| 4 | A gas drawn with more circles than the liquid it came from | Heating creates no new particles |
Instructions
- For each diagram, write what is wrong in one sentence.
- Then redraw it correctly, tracing every circle round the same coin.
- For diagram 2, write why the correction is right — not just what it is.
- Which of the four errors do you think you would have made? Answer honestly; it is not marked.
Why step 4 is not marked, and is asked anyway
Naming your own likely error is the beginning of catching it, and a learner who is being graded on the answer will not give a true one. Say it is unmarked before they start, and mean it.
Assessment
| Seen | What it means |
|---|---|
| All four named, all four redrawn with equal circles | Full understanding of the model as a set of claims |
| Diagram 1 caught, diagram 2 missed | The commonest pattern. The air error is subtler and is next week's work |
| Corrections drawn with unequal circles | The error is being described and reproduced at once. Trace the coin, out loud, together |
Activity 5 — The Energy Arrows (individual)
| Time | 15 minutes |
| Materials | Paper and pencil |
| Preparation | None. |
Instructions
- Draw three boxes in a row: SOLID · LIQUID · GAS.
- Draw arrows both ways between each neighbouring pair — four arrows in all.
- Label each arrow with its name, its energy direction, and whether the spacing goes up or down.
- Now add one extra arrow: straight from SOLID to GAS. What is that change called, and which way does the energy go?
The fifth arrow
Solid straight to gas is sublimation. It is not in the Grade 7 competency and it is not examinable — and a class that has just built the model can predict everything about it: energy in, spacing increases enormously, same particles throughout. Naming a change the model handles without ever having been taught it is the clearest evidence a model is doing real work.
Mothballs and dry ice are the usual examples; camphor, sold in most sari-sari stores, is the Philippine one.
Differentiation
| One step down | Two boxes — solid and liquid — and two arrows. |
| One step up | Add the sixth arrow, gas straight to solid, and name it. (Deposition.) |
Assessment
The four required arrows are the competency. The fifth is the interesting one, and a learner who reasons it out rather than recalling the word has understood what a model is for.
If there is no floor space, no cold surface and no coin
- No floor space for Activity 1 — run it with six learners at the front while the rest record. Rotate every four minutes so everybody has stood as a particle by the end of the week.
- No cold surface for Activity 3 — breath on a window, on a phone screen, or on a spoon that has been in a bowl of water. Every learner in the room has seen this and none has been asked to explain it.
- No coin to trace — a bottle cap, the end of a pencil, or a circle drawn round a fingertip. What matters is that the same object is used for every circle on the page.
- No chalk for the rectangle in Activity 1 — four school bags at the corners. The container needs to be visible, not permanent.
Part of the E-turo MATATAG artifact set. Companion files:
syllabus.md · lesson-plan.md ·
lesson-plan-ilaw.md · worksheet.html