How does one use appostrophe's etc in grammar when one doesn't have the foggiest about Grammar? Comma's are there to take a breath, anyone who has heard me speak knows I don't take breaths until the sentence is completed

As a present undergrad at uni I take offence at the assumption that we don't know how to string a sentence together or that it matters. The first thing after the understanding of the question when writing an essay, is and I quote " The correct use of Grammar and Spelling is pre-requisite for a good grade." We are taught though to write in a way that anyone with no command of the subject would understand it but without dumbing down.
Luckily for me, (who through having no interest in English in the written form ) I have a very patient set of people who read all my works prior to submission day and without whom I would be failing miserably although with their checks I am starting to get a grip of this new language and its appostrophes etc.
Who do I blame? Secondary education and more importantly myself
Rob