Reflecting and absorbing sound
Lesson details
Learning outcome
I can describe factors that affect how much sound a material or object might reflect or absorb, and explain ways to reduce noise.
Key learning points
- Sound reflects from hard surfaces. An echo is when a sound is heard again after reflecting and travelling back.
- Smooth, flat surfaces help to produce echoes. Irregular surfaces reflect sound in many directions, spreading it out.
- The particles of harder materials are held together by stronger forces so sound waves can’t make them vibrate much.
- Soft surfaces absorb a lot of sound because sound waves transfer energy by making the particles in them vibrate.
- Noise (unwanted sound) can be reduced by using soft materials to absorb it or hard materials to reflect it.
Keywords
Reflect - to ‘bounce’ off a surface
Echo - when a sound is heard more than once because sound waves have reflected back
Transmit - to pass into and through a material
Absorb - materials that absorb sound reduce the vibrations of the air (as sound is easily transmitted to/through them)
Noise - unwanted sound
Common misconception
Pupils often describe an absorbing surface as trapping a sound and do not correctly describe how the vibrations of air particles are reduced by making particles in a surface vibrate more.
Provide opportunity for pupils to describe how vibrations of air particles are reduced when sound waves make particles in a surface vibrate more.
Teacher tip
Echoes are heard best following a short loud sound, such as two blocks of wood being hit together or a short shout. There are excellent videos available online about sound proofing and 'anechoic chambers' (testing chambers designed to minimise echoes (reflections of sound) to almost zero.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of the following words describes a repeated back and forth movement?
Q2.Which of the following words is used to describe what all solids, liquids and gases are made of?
Q3.A drum on one side of a room is hit. It makes a sound that travels to the other side of the room. How does the sound travel across the room?
Q4.What is the name of the process when a wave ‘bounces’ off a surface?
Q5.What name is given to the process when a wave loses its energy after travelling into a material, so that it neither bounces off nor travels all the way through?
Q6.When a sound wave travels through air, it makes the air heat up a little.
Which of the following statements explains why this happens?
Assessment exit quiz
6 Questions
Q1.Which of the following statements are correct?
Q2.A person hits a drum in a room. After they stop hitting the drum, they cannot hear the sound any more.
Which of the following statements explains why this happens?
Q3.A person stands 5 metres away from a wall outside and claps. They hear an echo.
When the person hears the echo, how far has the sound wave travelled?
Q4.Which of the following characteristics of a surface allow it to produce clear echoes?
Q5.Which of the following is the correct definition of ‘noise’?
Q6.In a music recording room, echoes are usually not wanted.
Which of the following methods are most effective at reducing echoes in the room?
To help you plan your 7 science lesson on: Reflecting and absorbing sound, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 7 science lesson on: Reflecting and absorbing sound, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 science lessons from the Sound, light and vision unit, dive into the full secondary science curriculum, or learn more about lesson planning.