The AAT held, at para 32 of its reasons for decision:
"In the present case, I find that the dominant purpose of the applicant's overseas travel was to improve his knowledge and skill levels as a teacher for the purpose of enhancing his promotional opportunities within the school at which he was employed. I note that while non-mandatory expectations of overseas travel by the school would not of themselves justify the deductibility of the resultant expenses, the applicant in this instance undertook the travel with a view to supporting his colleagues in developing and improving a curriculum mandated by the State government and in attaining a level of extra-curricular professional activity consistent with standards also mandated by the State Government."
In allowing a deduction for 15 % of the cost of newspapers and magazines, the AAT held, at para 41:
"I accept the applicant’s evidence that he purchased the magazines and newspapers with the principal objective of using them in the course of teaching by searching for clippings relevant to his classes and for this reason some deduction should be allowed. However, there is a strong likelihood that he would have derived some incidental private benefit from the purchases. Presumably he was able – in part at least – to satisfy a natural intellectual inclination to read the daily newspaper in the course of scanning for relevant articles to put before his classes."
Lenten and FCT  AATA 281 (AAT, Dr Hughes M, 9 April 2008).
For a copy of the decision, go here