LIGHT AND DARK

LIGHT AND DARK, DAY AND NIGHT

•You probably don’t think much about light and dark. After all, you can turn on a switch and the lights go on. Even in the middle of the night, you can have light.

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•Two hundred years ago, though, people were very aware of light and dark. They worked during the day when the Sun was shining. As the sun went down, they used candles or oil lamps to see. However, these lights were dim. Outside, there were no street lights. The only light available came from the moon and stars. Night was very, very dark. People usually went to bed when the sun went down and woke up early.

What sources of light do you use every day? The sun is the biggest source of light. It warms the world so plants grow and animals can live. It allows you to work and play. Without the light of the sun, all life on earth would die. We also have electric light bulbs that bring us light. How about candles and flashlights? These light sources all need energy – from electricity, wax or batteries – to shine.

Light and Dark Vocabulary

1. Dim: dull, not bright
2. Shadow: a patch of darkness
3. Nocturnal: awake at night
4. Opaque: light cannot penetrate it. You cannot see through it.
5. Transparent: light can shine through it and you can see through it.
6. Translucent: some light shines through it and you can partly see through it

WHAT ARE SHADOWS

1. Your shadow is longest in the early morning and in the late afternoon. In the afternoon, when the sun is directly above you, your shadow leaves your side for a little while. The sun makes the longest shadows at the beginning and at the end of the day because at that time, the sun is lowest in the sky and aimed at the sides of the various things on the earth. When the sun is directly above you, there is little or no shadow because the light from the sun is falling upon you from all the sides and there is hardly any dark region.

Day and Night