Two things that change in Pip's life deal with education. He no longer feels good enough. Honesty and goodness aren't enough for him any more. He wants to be educated more than anything to impress Estella and win her over. So not only is he taking lessons from Biddy, but he is also getting help from Mr. Wopsle as well. That is the education that he is receiving for himself.
But learning himself is not enough. He wants to improve those around him, and Joe is his focus. He wants Joe to learn too. Joe is amused with Pip's teachings, but he doesn't seem to care about learning. He simply enjoys his time with Pip, so he goes along with him to "learn."
These two aspects of education show that Pip feels uncomfortable in the "world" that he has always been a part of. Until he met Estella, he was comfortable as a blacksmith. Now his world has been turned upside down and he wants to change not only himself, but those around him, too.