Someone has just used the word "criterion". Wow! 
Native language isn't English, of course. 
I went to school in the UK at a time when grammar wasn't taught; it was assumed that we would pick it up as we went along. Towards the end of Lower Sixth (Year 12 I think it is now), my father went to work in Australia, where the school year runs from February to November. I persuaded the school that I could jump up half a year rather than going back half a year and had to convert my Maths, Physics, Chemistry A levels into 4 Unit Maths, 2 Unit Physics, 2 Unit Chemistry and, horror of horrors, an English course. Given that I only had four months from starting school (6 days after I arrived in the country, the jet lag was still wearing off), they put me in the remedial English class (2 Unit A English), which I think was for those students who had difficulty trying to work out whether XXXX was a signature or a beer, as I only had to learn two books and two plays. It was in this class that, for the first time in my life, a teacher explained to me the purpose of (and distinction between) commas and semi-colons.
So, if there are any grammatical mistakes in this account, you have to blame various Secretaries of State for Education. (There were two notable incumbents of the role during my schooling - look up who was in the post between 20 June 1970 and 4 March 1974 and another between 10 September 1976 and 4 May 1979.)
