Wait, so how does this work for middle/upper class kids for whom the elaborated code is already close to their restricted code? Really, there are new ways of speaking being introduced to both groups. It's just a question of degree: how different is the elaborated code from the restricted code? My guess is that more different isn't necessarily better for learning. I'm certainly not going to learn anything if you try to lecture me immediately in Morse code, for example. Most likely there's an optimum level of divergence. Where does the optimum lie? I'm sure that teachers experiment with that on a daily basis...

So the benefit of the elaborated code for education doesn't come from making people learn a new style of communication. If they already know the elaborated code it's fine. It's about the fact that the elaborated code is designed to spell everything out explicitly, so it can communicate new information with less possibility of transmission error. The restricted code is designed to spell out as little as possible (it's more compressed based on knowledge shared by all users of the same restricted code.) That makes it better for day-to-day social interactions with in-group members (because the compression based on shared in-group knowledge binds the in-group more tightly together, and because the compression makes communication more efficient.)