A teacher was having a little trouble getting her year 11 pupils to understand grammar.
"These are what we call the pronouns", she said, "and the way we use them with verbs; I am, you are, he/she is..." she was saying, to glazed looks.
Trying a different tack she said, "Johnny, give me a sentence with the pronoun, "I" in it.
Johnny began, "I is..."
"No, no, no, no, no NO, NO!", shouted the teacher, "Never, 'I is', always, 'I am'... now try again".
Johnny looked puzzled and a little hurt, thought a while then began again more quietly,"I... am ...