Welcome to the fourth instalment of the ‘Making it Relevant’ series: Waves.
Firstly, we are going to take a look at why we teach Waves at GCSE. Then the content typically required in the new GCSE specifications will be summarised. Finally we will be thinking about how this can be made engaging and relevant to all our students. Planning a new scheme of work should involve looking at the big ideas you want to present, and then how to tailor them to your particular students.
Without waves, life on this planet would not exist.
The electromagnetic waves travelling to us from the sun sustain life. We are also harnessing the energy transferred by them in ever more ingenious and beneficial ways. We are all using the electromagnetic (EM) spectrum for communication everyday. Without the EM spectrum we would have no Wi-Fi, no mobile phones, no satellite communication, to name but a few. Our cooking habits see us utilising EM too; microwaves, toasters, grills.
The waves that travel through matter are equally important to our daily lives. Scientists are monitoring the seismic activity within the Earth to produce ever clearer models of the structure of the earth. Sound is keeping our ships from running aground and giving parents-to-be a sneak peak at their new offspring. Engineers are working on using the power of ocean water waves to generate electricity in a sustainable way.
Ideally, students should be finishing this topic with an appreciation for all the ways waves support and enhance our lives.
There are three main topics in the specification:
Basic Properties of Waves
The key terms that describe waves. Dull, but essential for calculations on wave-speed and time-periods. The basic idea that they are transferring energy from one place to another rather than the physical particles moving can be a misconception for some students. The similarities and differences between transverse and longitudinal examples. How different frequencies and wavelengths act at the boundaries between substances.
Waves in Matter
How waves transfer energy through matter and how we can make measurements of waves as they travel. How scientists are using waves to make observations of inaccessible objects. This includes: using seismic activity for exploring the earth; using sound for hearing; using sound for imaging and using sound for exploring the oceans.
The characteristics of all EM waves. How we are using the different regions of the EM spectrum. How the EM spectrum can harm us. There is a large section (in the Physics only specification) about using visible light and infrared. Reflection, refraction and lenses are included here; along with how we perceive colour and how filtering light affects what we see. Black Body radiation and how the balance between absorption, reflection and emission affects the temperature of an object.
It is tempting to start with the key terms of waves so that students are clear on what a wave looks like and how it moves. However, this is a rather dry entry to the subject. It might be more inspiring to consider starting the topic ‘backwards’. Looking at the uses and dangers of the EM spectrum will let students see the applications of this topic before the ‘maths’ is required. In fact, there is not much of the topic that you cannot teach without having met the wave equation.
There is a required practical about calculating speed and frequency of oscillations in air and water. Obviously, students do need a firm grasp of the mathematical properties of waves for this.
The uses and hazards of EM waves could be an ‘envoy’ activity with groups spending a lesson becoming experts in one use. Following this, the experts split up into new groups to spread their knowledge to everyone else.
For a homework you could try asking students to look round their homes for places where waves are used. As an extension can they try identifying the characteristics of the examples they have found (transverse/longitudinal, size, frequency etc.).
The use and effect of seismic waves could be a news type report done by groups. Each group can be given the same task but present their work in a different way (written report, poster, podcast, news paper/magazine article, class presentation etc.).
The properties of filters can be effectively demonstrated by showing students primary (and/or secondary) images on the projector screen. Then filters can be placed in front of the projector (taped to a metre-ruler and held up – not too close or they get very hot!) to demonstrate the appearance when each colour falls on the image.
This is a highly visual topic, so keep an eye out for opportunities to get your students generating some eye-catching display work too.