# CBT for Physics

### What are the Concepts for this subject?

The new course roadmap is neatly laid out with five broad conceptual themes:

A Space, time, motion

B Particulate matter

C Wave behaviour

D Fields

E Nuclear and quantum

Although these headings are not concepts in themselves, within each theme there are a group of linked concepts. There are also links between the concepts in different themes, but this framework of five themes is a very useful beginning!

Some concepts build on others and thus some are primary. Most physics courses would start with these primary concepts - often in theme A. The DP course however is flexible and, for example, it would be perfectly possible to start the course with theme C - Waves. Some concepts in physics are complementary to each other. For example, the concepts of momentum and energy are distinct yet there is mileage in comparing and contrasting them. The concepts of wave and particulate are distinct and in some ways contrary: unlocalised waves that move through each other are contrary to the impenetrability of localised particles.

Conceptual teaching is not new in physics education and many physics courses at this level outside IBDP have demonstrated how to do this kind of teaching. One particular example is the Nuffield A Level Physics course produced by the Nuffield Foundation, which started in the 1960s and was continuously revised until the 1990s.

Taking the example of theme C Waves, here is the roadmap:

C1 Simple harmonic motion (SHM)

C2 Wave model

C3 Wave phenomena

C4 Standing waves and resonance

C5 Doppler effect

The underlying concept of the wave is present in each section C1 to C5. It is mostly transparent in C2 wave model. In this section students study two contrasting examples of real waves: sound and electromagnetic. The fundamental idea of a wave as a travelling “disturbance” in a disturbed medium is reviewed (it is part of the assumed knowledge for this course). The nature of the medium for electromagnetic waves leads to linking questions with theme D Fields, and back again to ideas about relative motion in theme A. The idea that waves transport such things as information, energy and melody, but do not transport other quantities or qualities such as mass, charge or scent, provides a mirror-image for the theme A and B idea of the moving particle that transports mass, charge and scent, but not harmony.

This fundamental idea of a wave as a travelling disturbance is fleshed out in C3, C4, and C5, and the physical origins of physical waves are touched on in C1 SHM. The mathematical model encountered in C1 SHM gives students a means to access the mathematics in C4 standing waves. The mathematical model encountered in the C2 wave model allows students to work through to the formulae in C5 Doppler effect. Thus we see a conceptual map of this theme taking shape. The map links fundamental ideas to mathematical models to physical phenomena; i.e. a miniature representation of physics!

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