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Lesson overview
BUILD · Science · Week 4A · Explore

Muscles Work in Pairs

🎯 Learning objective: I can explain that muscles work in pairs to move a bone.
✅ Success criteria
  • Know that muscles pull rather than push.
  • Describe one muscle contracting while its partner relaxes.
  • Use a model to explain bending and straightening.
ArrivalStarterI DoWe DoI Do 2We Do 2IndependentExit
🧪 Movement Engineering⏱ 40 minutes🔁 Live Lundy loop
BEND: BICEPS PULLS STRAIGHTEN: TRICEPS PULLS
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
BUILD starts with safe participation and a familiar adult.
⏱ 4 min
🚪 Arrival · retrieve last lesson
Retrieve the actual previous lesson: Aut1·W3 — vertebrates have an internal skeleton/backbone that provides structure.
New to this class, or not sure? Everything you need is in the box above — read it, then answer.
◆ Supported

1 · Last lesson: Point to BACKBONE or NO BACKBONE for a snake.

2 · Last week: Point to the backbone on the fish picture.

3 · Week 3 again: Point to the crab’s hard case.

4 · Lead-in: Point to the place where the model arm bends.

▲ Standard

1 · Last lesson: A snake has no legs. Say why it is still a vertebrate.

2 · Last week: Name one vertebrate and one invertebrate.

3 · Week 3 again: Say how a crab is supported with no backbone.

4 · Lead-in: The skeleton holds the body up. What do you think makes it move?

★ Stretch

1 · Last lesson: Give the rule you used last lesson to classify a strange animal.

2 · Last week: Explain what makes an animal a vertebrate.

3 · Week 3 again: Explain one way an invertebrate is held up without a backbone.

4 · Lead-in: A bone cannot move itself. What might pull it? Say what you think.

Arrival retrieves. It does not assume today’s new concept. W4 has one prior taught week, so question 3 retrieves week 3 a second time.
BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Predictable retrieval; if access is blocked, change the mode before increasing demand.
⏱ 4 min
🌱 Starter · create the need to know

🔍 Today’s puzzle

A string can pull a cardboard lever, but can it push it? Test the idea on the model before we name the muscle rule.

FRAME 1 / 4
PULL THE TOP BAND
Pause whenever pupil Voice changes what should happen next.
FRAME 2 / 4
THE ARM BENDS
Pause whenever pupil Voice changes what should happen next.
FRAME 3 / 4
SWAP THE PULLER
Pause whenever pupil Voice changes what should happen next.
FRAME 4 / 4
MUSCLES NEED A PARTNER
Pause whenever pupil Voice changes what should happen next.
BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Pupil Voice opens the new question before the teacher supplies the explanation.
⏱ 5 min
👩‍🏫 I Do · picture first
🧠 Watch the thinking — picture first, words after the idea lands.
🔤 Key wordsCONTRACTSshortens and pullsRELAXESreduces its pull while its partner worksMUSCLE PAIRtwo muscles producing opposite movements
Word help shows an everyday bridge under each scientific word — the scientific word always stays. TA route: say the bridge, then fade it as the pupil uses the formal term.
STEP Use a cardboard arm with two bands/strings. Pull the top band: the forearm bends.
STEP Name the modelled change: biceps contracts/shortens; triceps relaxes.
STEP Pull the lower band to straighten: the jobs swap. Neither band ever pushes.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Teacher models; support staff watch regulation, access and the moment the idea lands.
⏱ 5 min
🤝 We Do · everyone commits
Commit before reveal: When the arm model bends, which statement is correct?
BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Adult genuinely receives the response; the next explanation/question/scaffold changes because of it.
⏱ 4 min
👩‍🏫 I Do 2 · connect the second idea
🧠 Watch the thinking — picture first, words after the idea lands.
STEP Make the invisible rule visible: a muscle can only pull, so paired muscles are needed for opposite directions.
STEP Contrast bend and straighten in two frames.
STEP Model one sentence with two linked jobs, not two disconnected facts.
✅ What this model helps us see

The arm model lets us see the two pulls swap.

⚠ What this model does not show

Card and string are not real body parts. It cannot measure force or show a full elbow.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Teacher models; support staff watch regulation, access and the moment the idea lands.
⏱ 4 min
🤝 We Do 2 · interactive lab
Interactive exploration: predict → manipulate → explain → adult receives → next move.

💪 Muscle Pair Lab

PREDICTTESTFREEZE & LOOKEXPLAIN
Simple elbow muscle-pair modelUpper arm, forearm and two patterned muscle paths. The forearm has three set positions. The text readout repeats every state.PINK SOLID = BICEPSBLUE DASHED = TRICEPSMODEL POSITION

1 · Predict which muscle pulls. Then test:

2 · Or move the model yourself. Every control is a button — no dragging:

Biceps: press a control first
Triceps: press a control first
Choose a prediction before the result is shown.
BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Adult genuinely receives the response; the next explanation/question/scaffold changes because of it.
⏱ 10 min
✏️ Independent · evidence of learning

✏️ Independent product / demonstration

Movement engineer. Build a model arm. Or label one that is built. Bend the arm. Show which muscle contracts. Show which muscle relaxes.

🧪 PRACTICAL READY · HANDS-ON WHERE IT SERVES THE OUTCOME
EquipmentCardboard arm models; split pins; string or yarn; biceps/triceps labels; pre-assembled models; projector model.
Safety / sensoryTeach on models/diagrams, not pupils’ bodies. Pre-assembled versions remove fine-motor barriers. Strings stay short and away from face and neck.
Evidence targetYour labelled model and your demonstration. A photo with your words, an adult watching, or your words scribed.
10 minutes. Supported / Standard / Stretch are routes, not fixed identities.
◆ Use a built arm. Place the CONTRACTS label. Place the RELAXES label.
Two labels only. CONTRACTS = pulls. RELAXES = not pulling now. Word bank: pull · bend · muscle · pair.
Fade it: remove the first prompt no longer needed.
▲ Work the model. Then say how the arm bends. Or write it down.
Stem. ‘When the arm bends, ___ contracts and ___ relaxes’. Swap the two for straighten.
Fade it: remove the first prompt no longer needed.
★ Explain the bend. Explain the straighten. A muscle can only pull. So why do you need two?
Use the words ‘muscles only pull’. So one muscle cannot push the arm back. Explain why the pair is needed.
Fade it: remove the first prompt no longer needed.
1 · Pupil decisionchoice, prediction, plan or classification
2 · Observable Sciencesort, model, demonstration, result or re-attempt
3 · Pupil meaningexplanation, justification or changed response
BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
Pupil authors a choice, model or demonstration; staff fade prompting and receive the Science.
⏱ 4 min
🎫 Exit · adult Audience closes BUILD
◆ Supported

Complete: muscles work in a ___.

▲ Standard

When the model arm bends, what does the triceps do?

★ Stretch

Explain why muscles need partners if they can only pull.

🔁 BUILD Lundy close

The pupil responds in a workable modality. The adult genuinely receives it — reads, listens or watches, and names back the Science they heard. The adult then calibrates the next learning move.

No extra pupil-written closure line is required for BUILD. If local policy uses an R code, it only belongs after genuine Audience; this file never adds it automatically.

BUILD Voice can be
☝ point / choose🗣 say / sign🧩 demonstrate / model✍ write / draw🔁 re-attempt
You can change how you answer. The Science goal stays the same.
🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE
BUILD closes through genuine adult Audience. Influence is the next calibrated learning move.
🧑‍🏫 SUPPORT STAFF · THIS SLIDE

ONE SCIENCE RULE

A muscle can only PULL. Every correction comes back to that.

Priority now

Move learning forward

Least prompt first
waitself-promptvisual cuegeneral verbalspecific verbalmodeldirect support

Move right only as needed, then fade back left. Support level records access. It does not define ability.

🔁 BUILD LIVE FEEDBACK–RESPONSE LOOP

Response changes what happens next

SPACECo-regulation, familiar adult, time, sensory tools, no public comparison.
VOICEPoint, sign, say, demonstrate, re-attempt, edit or authorised short clip.
AUDIENCEAdult genuinely watches/listens/reads and names back what was received.
INFLUENCECalibrate the next try, instruction, regulation choice, question or scaffold.

Choose the teaching move

Listen first. The response decides the next teaching move.

Uploaded-policy code reference · staff side

VF · verbal feedbackWS · worked with supportI · independentNS+ · one next stepE · evidenceR · responded / Audience happened// · self-edit? · read this back

This lesson stores no code or pupil response. R is never automatic and only follows genuine Audience.

BUILD Science W4A · Muscles Work in Pairs

Name: _______________________________   Date: ______________________

New to this class, or not sure? Everything you need is in the Retrieval box below — read it, then answer.

Learning objective: I can explain that muscles work in pairs to move a bone.

Model: helps us see — The arm model lets us see the two pulls swap. Does not show — Card and string are not real body parts. It cannot measure force or show a full elbow.

Previous lesson retrieval: Aut1·W3 — vertebrates have an internal skeleton/backbone that provides structure.

Arrival (Supported forms): 1) Point to BACKBONE or NO BACKBONE for a snake.  2) Point to the backbone on the fish picture.  3) Point to the crab’s hard case.  4) Point to the place where the model arm bends.

Supported

◆ Use a built arm. Place the CONTRACTS label. Place the RELAXES label.

Two labels only. CONTRACTS = pulls. RELAXES = not pulling now. Word bank: pull · bend · muscle · pair.

Standard

▲ Work the model. Then say how the arm bends. Or write it down.

Stem. ‘When the arm bends, ___ contracts and ___ relaxes’. Swap the two for straighten.

Stretch

★ Explain the bend. Explain the straighten. A muscle can only pull. So why do you need two?

Use the words ‘muscles only pull’. So one muscle cannot push the arm back. Explain why the pair is needed.

Evidence target

Your labelled model and your demonstration. A photo with your words, an adult watching, or your words scribed.

Exit + BUILD Audience

Supported: Complete: muscles work in a ___.

Standard: When the model arm bends, what does the triceps do?

Stretch: Explain why muscles need partners if they can only pull.

Adult Audience: the adult truly receives the response. The adult says back the Science they heard or saw. Then the adult picks the next learning move. No pupil signature is needed.

Evidence capture sheet · W4A · Muscles Work in Pairs

Date: ____________________   PUPIL / EVIDENCE ID: ____________________

Learning objective: I can explain that muscles work in pairs to move a bone.

Optional one-page capture. Point, say, draw or have an adult scribe — writing is never required. This sheet adds to the tiered pack; it never replaces it.

My decision

What I observed

Evidence I used

What the evidence means

What I changed after checking

Audience — who received it

What changed because of my voice

Teacher / TA comment