How do you teach turnback protection?

Good question Coach. It will reveal my lack of knoweldge by asking what you mean by a full reach? I'm guessing you are referring to a reach block.

What I know but don't see discussed in any of the threads devoted to slide schemes is a hinge technique in which the OL first step laterally toward the PS -- extending their PS arm at the same time -- and seal the PS gap. If nothing shows, they hinge so that they're angled and facing the BS, channeling upfield any defender who penetrates their area and attempts to cross their face.

In this context, turnback means: "turn your back" to the PS and block and area. I apologize if my understanding of terminology confuses the isse here. From my reading of the other "turnback" thread it's not the hinge technique I describe here.

If you could explain what is meant by "turnback" -- the technique involved -- I'd appreciate it.