It's actually a pretty common abbreviation these days, usually used by the media in order to both shorten the term and sensor it as it can be triggering for some people to even see or hear the full word.

Wow 6th grade? Seems a little young for something with a more heavier message. When I was in 6th grade, pretty sure I was reading books along the likes of The Hunger Games. Not a book focusing around the massive societal issue of racism and their injustices within our country.

I, as well as most people I know, started reading American literature around 9th-10th grade. Even then, there was a good amount of hidden messages/themes that would fly by students' heads. So I can't imagine how a 12 year old would handle analyzing something like this.

Sexual Assault