> The hardest part about learning a language is knowing what to learn. I disagree with this. The hardest part about learning a language is finding content and resources in the target language that are both engaging and comprehensible at your current level. It's hard to find books, shows, or conversation partners, all the way through that critical awkward stage from beginner to vaguely proficient. The parts of the lan…
Children's books? Children also learn from scratch. I think an adult reading books targeted to progressively higher ages would do reasonably.