ch35 the sounds of English
ch36 stress, rhythm, and intonation ("note the Oxford comma")
ch37 teaching pronunciation
ch38 vocabulary
ch39 text grammar
ch40 professional development and finding a job
p 178 says prioritise - decide what the main activity of the lesson should be. (for example, reading or speaking or writing or reading. For "systems" or "language" lessons, there is another list of possibilities, e.g. grammar, or situational language - but Thornbury does not mentions that here). Make sure that your plan foregrounds this core activity.
I think this is massively bad advice. I think it discredits the whole CELTA course to promote this idea. Where did this idea come? Some "extreme right" think tank? How did it come to infest CELTA?