Szymborska's poems

I mean it depends on the child, when I was in sixth grade I could read pretty much every book I can read now and did and I'm glad I read it as a child and had no problem understanding it, and many other children also have no problem understanding it ever since it came out. if you didn't know enough about the history of racial oppression it's your educational system's fault, especially if you actually live in the US but often in other countries we learn more about that than the locals in some places

recently I loved We have always lived in the castle by Shirley Jackson, The girl with all the gifts by Carey and You let me in by Bruce

Basically every Octavia Butler book, I love them so much. The most famous is kindred which is about real life slavery but it is not the most intese, I love all of them but the really soul crushing ones are probably Wild Seed (and the patternist series in general) and The whole Xenogenesis series (Dawn, Adulthood Rites, Imago). They all have themes of slavery and doing your best to survive and find a way out while utterly powerless, forced to deal with terrible things knowing that even dying would not change anything and so adapting to a terrible situation. There's usually a protagonist that values freedom, ethics, being a good parent, their people, and then a kind of coloniser character who has all the power and enslaves them, making them do all the things they would do anything to stop but they know that even if they died those things would still happen so they survive and try to do some damage control but ultimately they can't win

the reason they are so short is the advent of ebooks is also that of novellas. you may have noticed there have recently been many amazing books in the novella format, especially published by Tor. Before novellas were a problem because making them costs as much as any book and therefore they cost as much as any books to buy, as you will know if you bought the physical copy. Now though ebooks are common and this finally allows writers to write novellas. Tor also has very pretty covers and hardbacks that don't immediately run out, which really works for me as I tend to read the ebook first and only if I love it passionately to buy the physical copy. I love the monk and robot series and all her books :)