Light and shadows

For grown-ups: this lesson in words

Years 3 to 6 · Science

Light and shadows: I can explain how we see, how light reflects, how to keep my eyes safe, and how shadows form and change.

1. We need light to see. The lamp is a light source: it gives out its own light.

   Light travels from the lamp in straight lines. The arrows show which way it goes.

   The light reaches the ball and bounces off it.

   Then the light travels into the eye. That is how we see the ball.

   Picture: A lamp at the top left. Arrows show light travelling in straight lines from the lamp to a ball, then bouncing off the ball into an eye. Labels: light source, ray, object and eye.

2. Dark means there is no light at all.

   Our eyes do not make light. They need light coming into them to see.

   So in a completely dark place, no light can bounce into our eyes, and we cannot see anything.

3. Your turn: Sam is in a room with no windows, and the light is switched off. It is completely dark. Why can Sam not see anything?

   Choose one:

   • Sam's eyes have stopped working.
   • There is no light to go into Sam's eyes.
   • The dark is covering everything like a blanket.

   Answer

   The answer: There is no light to go into Sam's eyes.

   There is no light, so no light can bounce off things and into Sam's eyes.

Words to know

light source:

Something that gives out its own light, like the Sun or a torch.

dark:

When there is no light at all.

reflect:

To make light bounce off a surface, as a mirror does.

opaque:

Blocks light. Light cannot pass through it.

shadow:

A dark shape where an object blocks the light.