1. Light and shadows

2. Questions to think about…
How are we able to see the objects around us?
Why are we able to see through some objects but not others?
What are sources of light?
How are shadows formed?
Why do we need light?

3. Why do we need light? Light is a form of energy.
We need light to see things around us.

4. What are sources of light?
Objects that give off light are known as sources of light.
During the day, the Sun is our main source of light.
The Sun gives off its own light.
It brightens our surroundings and helps us to see the things around us.
At night, we use other sources of light to help us see.

5. How are we able to see the objects around us?
Although most of the things around us are not sources of light, we can still see them.
This is because these things reflect light into our eyes.
When light bounces off something, we say that light is reflected.

6. Why are we able to see through some objects but not others?
Look at the objects below.
They are made of materials such as wood, metal, some types of plastics, cardboard and clay.
Such materials do not allow any light to pass through them.
We cannot see through these objects at all.

7. Why are we able to see through some objects but not others?
Look at the objects below.
They are made of materials such as paper, some types of plastics and cloth.
Such materials allow only some light to pass through them.
We cannot see through these objects clearly.

8. Why are we able to see through some objects but not others?
Look at the objects below.
They are made of materials such as glass and some types of plastics.
These materials allow most of the light to pass through them.
We can see through these objects clearly.

9. How are shadows formed? Light travels in straight lines.
A shadow is formed when light is partially or completely blocked by an object.

10. Shapes of shadows
The shadow of an object usually has the same shape as the object.

11. Shapes of shadows
The shape of the shadow changes when the light source shines at different parts of the object.

12. Sizes of shadows
The size of a shadow changes if the distance between the light source and the object changes.
When the light source is moved closer to the object, the shadow of the object becomes bigger.

13. Sizes of shadows
The size of a shadow changes if the distance between the light source and the object changes.
When the light source is moved further from the object, the shadow of the object becomes smaller.

14. Sizes of shadows
The size of a shadow changes if the distance between the object and the screen changes.
When the screen is moved closer to the object, the shadow of the object becomes smaller.

15. Sizes of shadows
The size of a shadow changes if the distance between the object and the screen changes.
When the screen is moved further from the object, the shadow of the object becomes bigger.

17. The end