How can I understand Aquinas' Natural Moral Law theory?

In order to respond to this question, I shall begin by eliciting the students' existing knowledge on the matter. I may ask, 'what can you tell me about Aquinas' theory?' Depending on the response, I will emphasise some elements of the theory over others. If the student is strong at articulating Aquinas' belief in purpose, or of his formulation of a particular primary precept, then I will spend less time on that than gaps in their knowledge.
I shall breakdown the theory by slowly going over specific ideas, then demonstrate how they connect to each other. I will use visual aids to help the student's retention and understanding. For instance, I may use the acronym PROWL as a way of making Aquinas' primary precepts more digestible for the student. I shall use concept-checking questions throughout to ensure they understand. Finally, I may ask an evaluative question, like 'what do you think of this theory? Why?', as this prepares them for the critical thought required for higher marks.