Opening

BUILD · SCIENCE · Lesson 7 of 10

Build a screen silhouette

Learning intention

Explain that a shadow forms where an object blocks light from a source.

You need a clear dark shape.

Which material should you choose?

Use the light evidence.

Success looks like

Place a blocker between source and screen.
Explain a shadow using blocked light.
Use evidence to compare materials without overclaiming.

Retrieval

BUILD · SCIENCE · Lesson 7 of 10

Three clues for our design

1. Name a light source.

2. What does a surface do when it reflects?

3. Can a card block light?

I do

BUILD · SCIENCE · Lesson 7 of 10

I start without a blocker

The source sends light to the screen.

Light reaches the tested area.

An open light path

Diagram description

Three rays from a small light source reach a screen with no card in the path.

I do

BUILD · SCIENCE · Lesson 7 of 10

I put a card in the path

The opaque card blocks light.

Less reaches part of the screen.

That darker area is the shadow.

Light is blocked

Diagram description

Side-view light-ray model. Ray arrows point away from a small source. Boundary rays pass the top and bottom edges of an opaque card and locate the shadow on a screen.

I do

BUILD · SCIENCE · Lesson 7 of 10

Materials let different amounts through

Opaque: light is blocked.

Translucent: some light passes.

Clear: much light passes.

Materials change the light reaching the screen

Diagram description

Schematic comparison of opaque card, a translucent sheet and clear plastic. Arrow counts are qualitative, not measured percentages. Clear materials may still cast faint shadows.

Continue within this stage’s shared time.

We do

BUILD · SCIENCE · Lesson 7 of 10

Choose a silhouette material

Go to interactive investigation

Read the test cards.

Choose for a dark silhouette.

Point to the evidence.

Constructed teaching evidence
Card	Sample	Constructed observation
A	Opaque card	Clear dark shape
B	Translucent paper	Lighter, less distinct shape
C	Clear plastic	Most light passes; faint edge visible

W1. Which sample fits our design goal?

My response — say it, sketch on paper or type

Test the silhouette choice

Predict the screen result, then reveal the model. Actual sample results can vary with material and lighting.

Decision 1 of 3

There is no card in the source-to-screen path. What should happen?

Choose, test, then explain together. Evidence diagrams appear only after your test. Diagram transitions explain the model; they do not represent real elapsed time. Use Pause model to stop transitions and model controls, or your device’s reduced-motion setting. The printed We do activity provides the paper route.

We do

BUILD · SCIENCE · Lesson 7 of 10

The disappearing-shape challenge

The card moves out of the beam.

The source stays on.

Predict what changes on the screen.

W2. What explains the change?

My response — say it, sketch on paper or type

Hinge

BUILD · SCIENCE · Lesson 7 of 10

Why is there a shadow?

Choose the account that follows the light.

You do

BUILD · SCIENCE · Lesson 7 of 10

Choose your investigation route

Choose and order the setup.

Record a design decision.

Repair a shadow explanation.

My response — say it, sketch on paper or type

You do

BUILD · SCIENCE · Lesson 7 of 10

Use the evidence

Read or point to one clue.

Record what it supports.

Keep your explanation short.

My response — say it, sketch on paper or type

Continue within this stage’s shared time.

You do

BUILD · SCIENCE · Lesson 7 of 10

Make your own science record

Complete your chosen route.

Use a diagram, words or speech.

Check one answer with the evidence.

My response — say it, sketch on paper or type

You do

BUILD · SCIENCE · Lesson 7 of 10

Check and improve

Does my answer match the evidence?

Have I explained why?

Improve one label or sentence.

My response — say it, sketch on paper or type

Continue within this stage’s shared time.

Review

BUILD · SCIENCE · Lesson 7 of 10

Lundy loop: improve our account

Choose how to share one idea.

Listen to another explanation.

Use evidence to improve our account.

What is a shadow made of?

My response — say it, sketch on paper or type

Exit

BUILD · SCIENCE · Lesson 7 of 10

Three quick checks

E1. What does an opaque card do to light?

E2. Where is the shadow in our setup?

E3. What changes when the card leaves the beam?

My response — say it, sketch on paper or type

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

Evidence: the screen test

Constructed observations. Same source, screen and sample position in A–C.

A • Opaque card

A clear, dark shape is seen on the screen.

B • Translucent paper

Some light passes through. The shape is lighter and less distinct.

C • Clear plastic

Most light passes through. A faint edge is visible.

D • Move the card away

The source stays on. The opaque card moves fully out of this beam path.

W1. Choose A, B or C for a clear dark silhouette. Give a reason.W2. Predict what D changes on the screen. Explain.

Route 1 • Make a shadow plan

Word bank: source / card / screen / blocks.

S1. Which sample best makes a dark silhouette here? A B C

S2. Complete: The opaque card __ light.S3. Put these in order: source / screen / card.S4. Where do we see the shadow in this setup?S5. Explain what happens when the card leaves the beam.

Route 2 • Write the design record

Use the observations, or add your own if a practical runs.

Task	Sample	What does the evidence show?
T1	A: opaque card
T1	B: translucent paper
T1	C: clear plastic

T2. Draw source, card and screen. Mark where light is blocked and where the shadow is.T3. Explain why “clear plastic can never cast a shadow” is too strong.

Route 3 • Repair the display explanation

A display says: “The black card paints a black copy of itself on the screen.”

X1. Replace this with a light-based explanation.X2. Predict what a red opaque card of the same shape and size would do in the same position.X3. Why might a shadow look grey rather than completely black in a classroom?X4. Suggest a check that shows blocking, not coloured paint, causes the screen change.

Exit and reflection

Point, draw, write or tell an adult.

E1. What does an opaque card do to light?E2. Where is the shadow in our setup?E3. What changes when the card leaves the beam?R1. Which idea did you improve after hearing evidence?R2. What would you investigate or ask next?