They seem fine to me. I read a number of them in 7-8th grade and
that was back in ... 1984/1985. Some I read in 6th grade like
Huck Finn and Tom Sawyer. A few I read in 9th. I'd say it's on
target.
I've either read them all, or have a basic familiarity with
them. Call of the Wild was 7th grade and that book haunted me
for quite some time.
I also read "Clan of the Cave Bear" in 7th Grade. I didn't know
it was a prehistoric romance novel. To me, it was about this
first human lady and I was fascinated by the different culture
of the Neadrathals from what I was accustomed to. Thoroughly
enjoyed it.
I read the sexy scenes too but since it happened 125000 years
ago, I figured that was normal for the time and I knew it was
fiction in any case.
One teacher was a little scandalized that I read it. She was not
happy at all. I read it because it looked interesting in the
public library and you know what? It was.