I can only speak from personal experience, but most of the high school students I teach in Latin had (before they came to me) no idea at all what the differences are between consonants and vowels, never mind the distinctions between the types of consonants. When I explain the shift of 'n' to 'm' before plosives, and then explain what plosives are and why we call them that, it invariably prompts immediate "ooh"s and "aah"s before triggering a digression into all the English words they know that now "make sense" to them. There's also usually at least one student in the class for whom this revelation explains how the English prefix "im-" is the same as "in-" but they never knew it.
I'd give this all up and go teach basic English to small kids if I didn't know that I'd be drummed out in a week. But we do what we can, with a smile and a quiet sigh.
Tell us, too!