Lesson Plan

2. Describe the properties of sound

KS3-18-02

Intent

Learning Intention

  • Describe what affects the volume and frequency of sounds
  • Describe what a sound would be like by interpreting waveforms

National Curriculum

  • Learn that sound needs a medium to travel 
  • The speed of sound in air, in water, in solids

Working Scientifically

  • Ask questions and develop a line of enquiry based on observations of the real world, alongside prior knowledge and experience
  • Use appropriate techniques, apparatus, and materials during fieldwork and laboratory work, paying attention to health and safety  
  • Make and record observations and measurements using a range of methods for different investigations

Learning Outcomes

  • Describe what affects the volume of sounds
  • Describe what affects the frequency of sounds
  • Interpret waveforms on an oscilloscope

Resources

Resources: The handout and a 30cm ruler. 

Rocket words

  • pitch
  • hertz
  • oscilloscope
  • decibel
  • volume

Implementation

Prior Learning 

From KS2, the students should know that sound is produced by vibrations and travels in waves through different materials, but at different speeds. They should also know that pitch is determined by the frequency of the sound wave, with higher frequency sounds having a higher pitch, whilst volume is determined by the amplitude of the sound wave, with larger amplitude sounds being louder.

Starter

Ask the students how sounds vary and ask them to give examples of different sounds.

Main Teaching

Work through the presentation, answering questions as you go, to explore the difference between loudness and pitch and how it affects a wave. Discuss how the pitch and loudness change as a wave changes. The students can then complete the worksheet on how changing pitch and loudness affects the wave by interpreting the waveforms from the oscilloscope. Review answers as a class. The students should then complete the ruler twang investigation. There is an opportunity to stretch the students after the practical.

Career Film: Crossrail Apprentices: Zoe Conroy, Technician Engineer at Tottenham Court Road station

Expert Film: Watch the Expert Film with Jon as he demonstrates a Ruben's Tube.

Mission Assignment

Comparing sounds

On the handout, interpret the waveforms from the oscilloscope.

Ruler Twanging Investigation

The students will investigate how the length of the vibrating part of the ruler affects its pitch and volume. Give the students the following instructions: 

  1. Hang 5cm of your 30cm ruler over the edge of the desk.
  2. Flick the end of the ruler.
  3. Listen to the sound that is created.
  4. In your table, describe the sound you heard in terms of pitch and volume.
  5. Repeat as above for 10cm, 15cm and 20cm.

Differentiated tasks (Support/Challenge)

Support: Use an oscilloscope to model changes in sound. (Example -  https://academo.org/demos/virtual-oscilloscope/)

Challenge: There is a stretch task on the worksheet. The students can take the practical and re-write the method to make it more repeatable. 

Impact & Assessment Opportunities

Plenary

Review findings from the practical and then complete the questions on the end of lesson assessment quiz.

Teacher Mastery

Properties of sound waves

When an object or substance vibrates, it produces sound. These sound waves can only travel through a solid, liquid or gas. They cannot travel through empty space.

Longitudinal waves

Sound waves are longitudinal waves - the vibrations are in the same direction as the direction of travel.

Reflection

Sound waves can reflect off surfaces. We hear sound reflections as echoes. Hard, smooth surfaces are particularly good at reflecting sound. This is why empty rooms produce lots of echoes.

Soft, rough surfaces are good at absorbing sound. This is why rooms with carpets and curtains do not usually produce lots of echoes.