Didactic
All that didactic means, etymologically, is “instructive” or “skilled at teaching” (OED: διδακτικός). That meaning has persisted, neutrally, in some languages, where a departamento de didáctica or département de didactique simply refers to an education faculty, or Didaktik labels the theory of teaching. But the term, today, in English, is generally used polemically. To call a children’s book didactic is to accuse it of trying to impart a “message”—generally of a moral nature. Didactic, in children’s literature criticism and reviewing, is often synonymous with moralizing, authoritarian, totalitarian, propagandist. The term is also its own superlative: rarely is a book deemed “too didactic”; didactic generally suffices to condemn it.