Both of them are pretty tricky to master, because Thai operates very differently from English.
In the Relatives lesson, for example, an aunt is not just an aunt, but it depends on whether the aunt is your father's younger sister, or whether the aunt is your mother's younger sister, or whether the aunt is the elder sister of your father or mother. Each of these three different cases use a different word for aunt in Thai.
In the Telling the time lesson, you will discover that Thai groups times into different parts of the day, so for example, a word like 2 a.m. consists of the word early morning plus the word 2 (two), and the early morning part of the literal breakdown is shared only by the times from 1 a.m. to 5 a.m.. From 6 a.m. until 11 a.m. a new pattern is used with each of the words ending in o'clock and morning. In the evening, things get even more fun, as the numbers used for the hours are not even the same as that used in English. For example, 7 p.m. is literally hour 1 of the evening. Each of the words is carefully linked with "See also" links to all the related times, to try and make things as easy as possible.