Slackers in a Working Colony

As some of you may already know, 10% of an ant colony will always be slackers, and if you kill off those slackers, 10% of the remaining workers will become slackers. But what if you add in new slackers? The old slackers become the most efficient workers. I believe this works with humans as well. Why do I think so? Because I have experienced it first-hand. I was in a class with 30 people. 3 of the people were slackers. We were all at the bottom of the class, nearly never getting any work done. After we graduated from that school at the bottom of the class, we attended the next level of school. At this next stage, there were new slackers already there, and every single one of us slackers became extremely good at school.
All you have to do to be good at school, is be able to slack for the first 5-6 years of your education, and then suddenly stop being a slacker. How hard is this? Probably nearly impossible, but if I could do it, then you can probably do it as well... maybe.