Necessary, no fluff. Simply to make sure you are cut out for the job. They want to get a grasp of your initial teaching aptitude. Aside from competence, seemed they were also watching out for soft skills like patience and open-mindedness

The entire interview process was smooth, quick and efficient. There is also a teaching demonstration where the applicant has to demonstrate how s/he would teach a certain topic. Seems like they look out for people who are genuine in educating and passing on the knowledge and concepts to students, since there would be training provided for the technical aspects of teaching.