Science notes, unit 6

Light and dark

Textbook Science Year 2 (DLP), pages 61–72

What this chapter covers

{'You can name sources of light': 'the sun, lamps and fire (6.1.1)'}
You can say that it is easy to do things in a bright place and hard in a dark place (6.1.2)
You can say that a shadow is made when an object blocks light (6.1.3)
You can tell which objects make a clear shadow and which make a less clear shadow (6.1.4)
You can name shadow games such as wayang kulit and hand shadow play (6.1.5, 6.1.6)

We can see because of light. In this unit you will learn where light comes from, why we need it, and how shadows are made.

6.1Light and dark

Sources of light

A source of light is something that gives out light. The sun, lamps and fire are sources of light.

A sunny day with children playing hopscotch in a village yard — In the day, the **sun** is the main source of light.

Source	Examples
The sun	Sunlight. It is a natural source of light.
Lamps	Street lamps, car lamps, home lamps
Fire	A candle flame, an oil lamp, a torch

A village at night lit by street lamps, a car light, sparklers and a flaming torch — At night we cannot see the sun. Lamps and fire give light to dark places.

Did you know? Fireflies glow only at certain times, so we do not count them as a source of light.

Name two sources of light you can use at night.

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A lamp and a candle (or a torch, or fire).

Light and dark places

In a bright place, it is easy to do things.
In a dark place, it is difficult to do things.
In the dark we need a source of light, such as a torch.

The black box game

Two pairs find number cards inside black boxes. Box A has a torch. Box B has no torch. The pair with the torch finishes faster, because they can see the cards.

Do not point a torch at anyone's eyes.

6.2Shadows

A shadow is a dark shape. It is made when an object blocks light.

A family walking in a park, their dark shadows on the ground — The dark shapes on the ground are shadows.

Switch on a torch.
Put an object in front of the light.
The object blocks the light, so a shadow appears on the screen.

Did you know? Light from two sides makes two shadows of the same tree.

Clear and less clear shadows

Object	Light goes through?	Shadow
Thick paper, pencil, steel ruler	No	Clear
Tracing paper, glass, frosted glass	Some light	Less clear

A shadow is not made by the object alone. You need light too. No light, no shadow.

A shadow is made when light is ______ by an object.

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Blocked.

Shadow play

Wayang kulit is a shadow play. The puppet blocks light, so its shadow shows on a white screen. The shadow is clear and looks like the puppet. You can also make hand shadows with a torch.

A puppeteer holding wayang kulit puppets in front of a lit screen — A wayang kulit show.

A wayang kulit puppet and its dark shadow on a screen — The shadow looks like the puppet.

Pictures: Science Year 2 (DLP) textbook, pp. 62, 63, 66 and 69.

Summary

Idea	Remember
Sources of light	The sun, lamps and fire
Bright place	Easy to do things
Dark place	Difficult to do things
Shadow	Made when an object blocks light
Clear shadow	Thick paper, pencil
Less clear shadow	Tracing paper, glass