The IB Diploma
The IB course can be represented by a circle. The circle is divided into six sections, each representing one of the six diploma subjects. These six sections enclose the core of extended essay, theory of knowledge and CAS.
The 6 subjects are like petals of flower held together by the extended essay and TOK. You could argue that the extended essay should be in one of the petals since it is written in only one subject however the skills of essay writing used are relevant to all subjects so skills wise it should be in the middle. TOK fits well in the centre since it connects the subjects but I see CAS as all encompassing rather than at the centre. In this representation the petals are all separate however they should be interlinked, maths and science, language A and language B etc. in practice this is however not always the case and anyway it would spoil the picture.