It just goes to show that a little accurate spelling can go a long way. It's just unfortunate for the expletive-expressing teenager that he didn't decide to write a little more on his exam paper or he might have earned himself more than just 2 marks out of 27.
Match Wits with the Kids has a whole section on spelling, including a number of useful spelling rules and a list of those words which are commonly misspelled.
So, if spelling isn't your strong suit you could do a lot worse than pick up a copy of the book here. We just wouldn't recommend resorting to the Anglo-Saxon vernacular when it comes to putting it into practice.