PS RS P4L19 Light III WS

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Topic: LIGHT III (LESSON 19)

Rocket Science | Primary 4

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Primary 4: Rocket Science

Lesson Outline
• Notes
• Activity 1: Hands-on Activity
• Activity 2: MCQs
• Activity 3: Open-ended Questions
• Activity 4: Fun Facts Video

1

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Primary 4: Rocket Science

Shadows
What is a shadow?
Shadows are formed by a complete or partial blocking of a light source.
Light travels in straight lines. When it is completely blocked by an object, a
shadow will be formed.
A shadow is the area of darkness that is cast when light shines on an
opaque object. Light cannot pass through it. The shadow will have two
parts, umbra and penumbra.
Umbra – totally dark area as all light from the source is blocked by the
object.
Penumbra – less dark, lighter shadow as not all parts of the light is blocked
by the object.

Animation Lesson

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Primary 4: Rocket Science

Size of shadows can change
Size of the shadow changes when the distance between an object and the
light source changes.
If an object moves closer to a light source and further away from the screen,
the shadow gets bigger and less sharp.
When we position an object further away from the light source and closer to
the screen, the shadow gets darker, smaller and sharper.

Shadow gets smaller as the
opaque body is moved closer to

the screen

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Revision: Primary 4: Rocket Science
Opaque objects
• They are made of materials such as .
.
• Such materials include .
Translucent objects
• They are made of materials such as

• Such materials include
Transparent objects
• They are made of materials such as

• These materials include

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Primary 4: Rocket Science

Activity: Making an Kaleidoscope with a Plastic Report Cover

1. Draw a 20 cm by 10cm rectangle
on a clear plastic report cover.
This is going to be the base of
your Kaleidoscope. Cut it out,
using a pair of scissors. Draw three
horizontal lines across the
rectangle, splitting it into three 3 cm
pieces and one 1 cm piece.

2. Fold the plastic along the lines to
form a triangular shape. The
quarter-inch strip should stay on the
outside and act as a flap. Tape the
strip along the edge using
transparent tape so the triangle
holds its shape.

3. Slide the triangle into the
cardboard and create your
peephole. Cut a paper towel roll
down to 20 cm, the same size as
your triangle. Slide the plastic
triangle into the paper towel roll. To
create your peephole, turn the paper
towel tube on one end, standing
straight up. Trace a circle around it
on black construction or contact
paper. Then, poke a hole through
the center of the circle, using a pair
of scissors or a sharp pencil, and
making it large enough so you can
see through it. Tape the circle over
one end of the tube.

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Primary 4: Rocket Science

4. Cut out a four-inch square of
plastic wrap. Place the square of
plastic wrap over the other end of
the tube. Use your fingers to poke
it down into the plastic triangle,
until it forms a little pouch.

5. Fill the pouch with beads,
sequins, and confetti. Anything
small and shiny will do the trick,
but translucent objects are best.
You also want different shapes
and sizes. Your kaleidoscope
won't be shoved in a drawer
anytime soon if there's infinite
variations as to what can be seen.

6. Place a square of waxed paper
over the pouch. Place a four-inch
square of waxed paper over the
pouch and around the cardboard
tube, sealing in the beads and
sequins. Stretch a rubber band
over both the waxed paper and
the plastic wrap. Make sure it’s on
tight so nothing spills out.

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Primary 4: Rocket Science

7. Decorate the outside of your
kaleidoscope. You can use
stickers, wrapping paper, contact
paper, or construction paper.
Some contact paper looks like
wood, metal, or gold. But why stop
at paper? You could add glitter or
sequins on the outside too.

8. Use your kaleidoscope. Hold the
tube up to one eye, facing the
light, and look through it. Turn it
slowly -- what happens? It's your
own light show! The light is
bouncing back and forth against
your report cover, creating this
constantly changing display in
front of your very eyes.

https://www.wikihow.com/Make-a-Kaleidoscope

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Primary 4: Rocket Science

Activity 2 – MCQs

8

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Primary 4: Rocket Science

1) Jervin shone a torch at an object against a wall in the dark.
There was no shadow cast on the wall. What could Jervin have shone
the torch at?

(1) a mirror ( )
(2) a metal rod
(3) a piece of clear glass
(4) a sheet of tracing paper

2) Study the diagram below. Which period of the day do you think it could be?

(1) 8 a.m. ()
(2) 12 p.m.
(3) 3 p.m.
(4) 5 p.m.

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3) There is a cupcake in a box. Primary 4: Rocket Science
lamp cardboard box

cupcake

Which of the following explains why the girl cannot see the cupcake?

(1) Light cannot pass through the box. ( )
(2) The box reflects light into the girl’s eyes.
(3) The cupcake reflects light into the girl’s eyes.
(4) Light from the girl’s eyes cannot be reflected into the box.

10

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Primary 4: Rocket Science

4) The diagram below shows a cone used when roads are being repaired.
Part Y helps to make the cone more visible when light shines on it.

Part X Part Y

Which one of the following is true about part Y of the cone compared to
part X?

(1) Part Y does not reflect light. ( )
(2) Part Y can reflect more light.
(3) Part Y can give off more light.
(4) Part Y allows more light to pass through.

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Primary 4: Rocket Science

5) Ivan placed a torch at 4 positions, A, B, C and D, to form shadows of an
object.

A

BD

C

He drew the shape of one of the shadows formed below.

At which position had Ivan placed the torch to form the above shadow?

(1) A ( )
(2) B
(3) C
(4) D

1312

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Primary 4: Rocket Science

6) The diagram below shows three objects. The white area is transparent
and allows light to pass through. The grey area is opaque and does not
allow light to pass through.

The three objects were glued together. They were placed between a torch
and a screen as shown below.

torch star disc square screen

Which one of the following shadows is possible?

()

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Primary 4: Rocket Science

7) Jack placed three identical blocks of wood in front of a torch that he was
holding. He saw the shadows cast on the screen as shown below.

screen

side A side B

Which of the following (top view) shows how the blocks of wood were placed
during the experiment?

(1) side A

torch blocks of wood screen side B
side A
(2)

side B
(3) side A

side B
(4) side A

side B

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Primary 4: Rocket Science
8) Gwen looked through the peephole on the shoebox but could not see the

cube inside it. She was able to see the cube when she allowed the torchlight
to shine from inside the box.
Which of the following shows the correct pathway of the light rays?

(1)

(2)

(3)

(4) ( )

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Primary 4: Rocket Science

9) Study the diagram shown below.

Which torch,A, B, C or D, would most likely cause shadow H to form?

(1) A
(2) B
(3) C
(4) D

( )

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Primary 4: Rocket Science

10) Meiying shone a torch at the ceramic cup shown below from different
directions to form different shadows of the cup.

ceramic
cup

Which of the following shadows is not possible?

()

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Primary 4: Rocket Science

Activity 3 – OEQs
1) Mira shone a torch on an object as shown below. The shadow formed was

cast on the screen.

(a) Describe how the length of the shadow on the screen changes as the

object moves from position X to Y. [1]

(b) Besides moving the object, state what Mira could do to increase the size of

the shadow formed on the screen. [1]

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Primary 4: Rocket Science

2) David arranged set-up A with three pieces of cardboard, C, D and E in a
row. He then moved cardboard D so that the holes in C, D and E were no
longer in line as shown in set-up B.

cardboard
hole

candle

Set-up A Set-up B

What would he observe if he were to look through the hole in cardboard C in:

(a) set-up A? [1]

(b) set-up B? [1]

(c) State the property of light in the above experiment. [1]

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Primary 4: Rocket Science

Activity 4 – Fun Facts : Changing positions of the Sun and the shadows formed

https://www.youtube.com/watch?v=1SN1BOpLZAs

DISCUSSION QUESTIONS:

1) What cause the changes in
the length of the shadow?

2) Why is there almost no
shadow at noon?

3) Find out about why the sky
changes colour as the sun sets.

4) Draw a bar graph to predict the
length of shadow throughout the

day.

9a.m. 12p.m. 3p.m. 6p.m. Time of
day

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