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Sound - How Sound Travels
Objectives
To understand that vibrations cause sounds.
To understand that sound travels because vibrations travel.
To understand which factors cause louder and softer sounds.
Resources
Lined paper | Elastic bands | A long cardboard tube | A source of sound e.g. a ticking clock
Today's Lesson
Main Activity
Using elastic bands, help your child to make a primitive guitar by stretching the bands between two objects. Ask your child to pluck the bands to make them vibrate. Now stretch the bands further (so they are tighter) and ask your child to pluck them again. Discuss what you notice about the vibration of the bands (they will be faster) and the pitch of the sounds (they will be higher).
Watch the Making and Hearing Sound video and ask your child to explain how sounds and vibrations travel from the source.
Hold a source of sound (e.g. a ticking clock) next to your child’s ear so they can hear it. Move about a meter away and ask if they can still hear it. Was the sound louder or softer? Why? (Try to encourage your child to use the words vibrations, travel and air in their answer). Now try again but the time holding a long tube to your child’s ear with the other end reaching the clock. Was the sound louder through the tube? Why did this happen?
Ask your child to think of something else that makes a soft sound. Support them to think of different ways in which to amplify the sound (for example, by trapping it in a container, going into a smaller room, or having it vibrate against something that will help to make the sound audible). Plan a fair test to find out how to amplify this sound. List the materials you would use and the steps you would take. Explain how you would make it a fair test and decide how you would present your results.
Guidance for Parents:
Students must plan what they will measure in order to collect evidence. This is an important point to discuss before they start their experiment. They should also think about how to present their results.
An example of an investigation could be: Does everyone in my family/group/friends have the same level of hearing? They could use a cardboard tube and a ticking clock. The important things to encourage are keeping variables constant to make it a fair test. For example, everyone must stand the same distance from the clock to check if they can hear ticking.
They could make lines on the ground at different distances from the source of the sound and see which family/group/friends can hear the ticking at the different distances. They could present their findings in a bar chart or a table.
Or another example would be to collect/make an instrument that makes a quiet sound. Ask friends/family to cover their eyes and cover ears with headphones/ear defenders and sit on a chair. With their back to you, move 1 metre and hit/strike/shake the instrument or object you have. Can they hear it? Move another metre and repeat keeping the same volume; it cannot be hit louder or quieter. Can they hear it? Move another metre until they cannot hear it again.
Repeat with other family members/neighbour/friends. This is a fair test because you are asking the participants to sit in the same place/using the same sound source/trying to keep the volume the same/moving the same distance each time.