I'm not far off the age of the two in question, if they didn't take advantage of the education system when they had the chance I have no sympathy. I'm sure theres a few kids in the school you work at that you think probably don't deserve to be in your school.
At the end of the day you get out what you put in and things aren't handed to you on a plate. Until people realise this theres going to be the same "excuses" for years and years to come. Simple fact is, some people don't want to work, I know people like this and it doesn't make them any less of a nice person but it's a fact. They can moan about work to me until the cows come home but the simple fact is, there are chances and they just need to learn to motivate themselves and sort it out THEMSELVES.