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Summaries · Grade 4 Natural Sciences › Sound and light
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Sound and light

How sound is made by vibrations and how light travels in straight lines and makes shadows. Read one part at a time and tap “I know this”. Then test yourself in the quiz.

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Sound

Strike a bell and it vibrates. Hold it tightly and it goes quiet, because your hand stops the vibration. Strike harder for a louder sound. A drum vibrates more slowly than a whistle, so it gives a lower note.

  • Sound becomes softer the further you are from the source.
  • Wear earplugs at a loud concert to protect your ears.
Tap when you could tell someone without looking.

Light and shadows

The Sun makes its own light. Light travels in straight lines, so it cannot go around an object; that is why a shadow forms behind an opaque object. The closer the light is to the object, the bigger the shadow. In the evening, when the sun is low, shadows become longer.

Shadows with a torch: the closer the light, the bigger the shadow.
Shadows with a torch: the closer the light, the bigger the shadow.
Rule

Never look straight at the Sun: it can damage your eyes for good.

Tap when you could tell someone without looking.

Reflection

  • A shiny mirror reflects light best.
  • White clothes reflect sunlight and keep you cooler.
  • A pencil in water looks bent, because light bends as it enters the water.
Tap when you could tell someone without looking.

Remember this and test yourself

Remember this: your summary
  • Sound is made when something vibrates; it travels through the air to our ears.
  • In space there is no sound, because there is no air.
  • Light travels in straight lines. An opaque object blocks the light: a shadow.
  • Light bounces off a shiny surface: reflection. Sound bounces back: an echo.
  • We see lightning before we hear thunder: light travels faster than sound.

Write these points in your book. Read them again the night before the test.

Memory trick

Sound = vibrate, light = straight. Lightning always wins the race; thunder comes second.

Flash cards · Tap to turn over

Important words

First say what the word means, then turn the card over.

Test yourself · Part 2

True or false?

Read the question and the answer. Is the answer right? Tap True or False.

    Now the real quiz!

    The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.

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    For parents
    • Read one part together and ask your child to tell it back in their own words.
    • The ticks (“I know this”) are saved on this device only. We never ask for names or emails.

    Follows CAPS for Grade 4 Natural Sciences and Technology. Always check your teacher’s notes and textbook too.

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