I need to refute the claim that public schooling is "training to be slaves"? Really?

Yes, you do. Please read this: http://www.sethgodin.com/sg/docs/brainwash.pdf

Maybe "training to be slaves" is hiperbole, but as Seth Godin puts it, training to be "cogs in a machine" is quite right.

Slaves were, and are, born into poverty, often forcibly removed from their parents, treated and sold like cattle, worked hard at all times for no benefit to themselves, had no rights and no legal protections, and had no prospect of removing themselves from slavery. In no way is this comparable to receiving a relatively high quality education during the formative years of your life.

Teachers work hard for little reward to provide the education they give and it is a slap in their face, the faces of the descendants of real slaves, and the real slaves that continue to exist today, to imply that the good work they do is equivalent to what slave owners and masters did to their victims. The analogy to slavery is disgusting and juvenile and it's ludicrous that I had to explain this to you.

Yes, you are right, school do not train for slavery literally. But that wasn't the point. As you've recognized yourself, it was an analogy.

As an analogy, you can't say it is invalid by stating differences between the analogues, all analogies are pretty much aware of these differences. If not, they would be identities, not analogies.

"Juvenile", "disgusting" and "ludicrous" are not arguments sufficient to invalidate the analogy either.

What you have to do to invalidate the analogy is to refute the similarities between schooling and slavery, some of them:

  - kids are forced to go to school;
  - kids are brainwashed to think that school is the only alternative they have besides starving and ultimately dying after an horrible life;
  - kids are trained to be submissive to teachers and other in liderance positions.