Light and Shadows

Grade 1 · Science · Study Guide

Explore how light travels and how shadows are formed.

Light helps us see the world around us. The sun is the biggest source of natural light on Earth. We also make artificial light using lamps, flashlights, and candles.

Light travels in straight lines. That is why you cannot see around a corner without a mirror. When light hits an object, different things can happen.

If an object is transparent, like glass or clear water, light passes through it. If an object is opaque, like a book or a wall, light cannot pass through. When light is blocked by an opaque object, a shadow is formed on the other side.

A shadow is a dark area that forms when an object blocks light. The shadow is always on the side of the object away from the light source. If you stand in the sun, your shadow appears behind you or in front of you depending on where the sun is.

The size of a shadow changes depending on how close the object is to the light source. If you hold your hand close to a lamp, the shadow is big. If you move your hand farther away, the shadow gets smaller.

Shadows also change size throughout the day. In the morning and evening, when the sun is low in the sky, shadows are long. At midday, when the sun is high, shadows are short.

Key terms

light
A form of energy that lets us see things
shadow
A dark area formed when an object blocks light
transparent
A material that lets light pass through it
opaque
A material that blocks light and creates a shadow
light source
Something that produces light, like the sun or a lamp
reflect
When light bounces off a surface

Flashcards

Light
Energy that lets us see; travels in straight lines
Shadow
A dark area made when an object blocks light
Opaque
Blocks light; creates a shadow
Transparent
Lets light pass through; no shadow
Light source
Something that makes light, like the sun or a flashlight
Reflect
When light bounces off a surface
Natural light
Light that comes from nature, like sunlight or fire
Artificial light
Light made by people, like lamps and flashlights

Questions

  1. What is the biggest natural source of light on Earth?

    1. The moon
    2. Stars
    3. The sun
    4. Fire
    Show answer

    Answer: The sun

    The sun is the largest and most important natural source of light for Earth.

  2. Light travels in straight lines.

    Show answer

    Answer: True

    Light always travels in straight lines, which is why we cannot see around corners.

  3. A shadow forms when an object _______ light.

    Show answer

    Answer: blocks

    When an opaque object blocks light, a dark shadow forms on the other side.

  4. When are shadows shortest?

    1. In the morning
    2. At midday
    3. In the evening
    4. At night
    Show answer

    Answer: At midday

    At midday the sun is highest in the sky, so shadows are the shortest.

  5. A shadow forms on the same side of an object as the light source.

    Show answer

    Answer: False

    A shadow forms on the opposite side of the light source — the dark side of the object.

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