IC I think I see where you're coming from but he didn't mean a school building or a physical teacher.
I don't know about you, but I'm learning so much, I'm a new person every month. We're learning that we're all one, that "To transcend it...leave it all behind" or in my case, 'it's all an illusion' from many different sources throughout our lifetime. We all are learning our own lessons.
There are basic cosmic laws we're all learning like attraction, gravity, macro and quantum mechanics, psychological and emotional and most of them we don't learn in a physical school or from people.
Paxton meant all of this life we live on earth is a school or lessons.