Meanings
instructive, instructional (serving to teach information, typically a specific lesson)
moralizing, patronizing, preachy (trying to instruct, often with a copmponent of morality, when doing so is regarded as disrespectful or arrogant)
Bei aller wünschenswerten politischen Gegenwartsnähe dürfe das Jugendbuch aber nicht von aufdringlichen politischen Tendenzen beherrscht sein. Auch sollten die Jugendbuchautoren einen allzu belehrenden Tonfall möglichst vermeiden.For all that relevance to the political present is desirable, the book for adolescents should not be dominated by presumptuous political tendecies. Also, authors of such books should avoid a tone that is rather too moralizing, if possible.