After the 60s and 70s it was not the done thing to teach grammar. By grammar, I am not talking metaphors, similes and the like, but what is a noun, an adjective, a preposition and so on - how to deconstruct the language.
My father, Ninian Smart, died before he was able to complete his autobiography. I still have a copy of the first section he wrote where he describes his early lessons at King's College Choir School (probably around 1936/7) in Cambridge.
Now that school in those days was ruled by a headmaster, one Mr Cedric Fiddian, who was batty and in his own way a genius. He had white hair and had been what they called 'shellshocked' in World War I, in the trenches. His visage was genial but a bit chimpanzee-like. Fascinated by shellholes, he had constructed two or three open air classrooms round the school. One was his favourite: a round affair scooped out of the earth, where he had desks and chairs arrayed. There he loved to address the classes on Latin or other topics.
He had a good way of teaching that language. First he would get you to underline each adjective, verb, noun, etc, in some usual text (normally Tennyson). After that he would set you on to Latin verbs such as 'stick-in-the-mud-o, stick-in-the-mud-are, stick-in-the-mud-avi, stick-in-the-mud-atum'. It was easy to remember, a bit humorous and built up to the next stage.
Note that before the boys could identify the parts of language in Latin, they had to be able to identify them in English.
I wonder whether any foreign language course should not begin with at least 5 or 6 lessons devoted to examining the English language and how it works. Once that has been understood, it can be time to move on to the foreign language.