Perhaps we are lucky. Even our slowest Latinists in the junior forms—those who will prefer Classical Civilisation to Latin for GCSE—seem to be enthused by the challenge of learning a vocabulary.
Before starting to memorize, it helps if they are secure with the parts of speech. Attached (see Grammar in the menu) is a Parts of Speech template, which of course can be adapted or improved upon. It does not deal with words that can be used in different functions, especially prepositions that can be used as adverbs and vice versa. More on this later.
But as for nouns: an American journalist remarked that any noun can be verbed, and an observant child will soon notice that.
It was for Indo-European languages that our ancestors devised the attached classification. It may not be valid for other languages, and some colleagues may query the system anyway, given some modern theories of linguistics. The reply seems to be that until a better system is devised, this must suffice.
Children like order, and to know how things work; and under this system the basic grammatical functions are reassuringly finite.
We have found it useful to arrange vocabulary lists by the parts of speech. Even at AS stage, or perhaps especially so, it seems to make sense of the learning and render it less of a chore. It also makes patterns of formation more visible.
Please see the AS and GCSE Latin wordlists arranged in this way on the Wordlists page.