Gifted young wordsmiths may enjoy reading the online articles on various aspects of the English language, at WordSmarts:
https://wordsmarts.com/
Topics are categorized, such as Language, Vocabulary, Idioms, Slang.

Various aspects of history and changes over time have been especially interesting to me, including:
https://wordsmarts.com/meaning-50-years-ago/
https://wordsmarts.com/grammar-rules-forget/