KS2 SATs Science: Light and Sound Guide

How we see

Light travels in straight lines from a source, and we see objects when light reflects off them and enters our eyes. Light cannot travel through opaque objects, which is why shadows form on the opposite side from the light source.

Shadows

A shadow forms when an opaque object blocks light. The shadow is the same shape as the object blocking the light, and gets larger as the object moves closer to the light source.

How sound travels

Sound is made when something vibrates. These vibrations travel through a medium (like air, water or a solid) as sound waves until they reach our ears.

Pitch and volume

Pitch depends on how fast something vibrates — faster vibrations make a higher pitch. Volume depends on the size of the vibrations — bigger vibrations make a louder sound, and sound gets quieter the further you are from the source.

Common mistakes

• Thinking we see because light comes out of our eyes, rather than light entering them.
• Confusing pitch (how high or low) with volume (how loud or quiet).
• Forgetting that sound needs a medium to travel through — it cannot travel through a vacuum.