Design and content
We need to classify the large number of things we teach (just as we classify large numbers of anything else) because the smaller sub-groups are easier. to deal with. Once a classification has been made and used however, it does tend to stick. We often get to think that things are classified like this. We do not look for possible revisions of the classifications although we would be ready to look at revisions of a scientific principle or of a teaching method. When we get used to particular names for these sub-groups we also resist changes in usage or terminology: they are very upsetting. Change in nomenclature is bad enough when it is a simple replacement of one term by another, as for much of the recent revision of the terminology of chemistry, or the big rationalisation of terms undertaken for the Textiles Industry.9 It is however much worse when the change in meaning is small and subtle. I am going to suggest in this article that our present rather vague classification into design and content ('the rest') should be replaced by one that is slightly more complex.