For me, it was explaining the learning process. For example, be ready to explain and give examples of the Law of Primacy.

There is one more thing. In those days, examiners had a quota in that they had to fail a certain number of their CFI examinees. He failed me for something trivial, then had me come back the next day and passed me within ten minutes. He just had to get that "fail" on his record and then he was happy. (I am curious to hear if this is still happening.)