Well, it depended on the school.
I went to school in Broomfield. Boulder Valley School District RE-1. They taught us about the Sand Creek Massacre in Colorado History Classes. Since your ddw went to school in Boulder the lack of mention of the Sand Creek Massacre doesn't surprise me. Back when it happened Col. Chivington (also a Methodist Minister) was looked on as a Hero by the residents of Colorado.
The Movie version was made by Hollywood in the late '60's. It was called "Soldier BLue" and starred a young Candice Bergen. Of course, much as in the movie "Dancing with WOlves", the Milita was made out to be ignorant, bloodthirsty and generally barbaric. And so the PC Pendulum Goes. I wonder how Cecil B. DeMille would have portrayed Union Pacific if it had to be made today.
Of course, I went there from 1959-1970 before we had to be Politically Correct and self-flagellating (sp) about everything that was done by the settlers (now called invaders and interlopers) of Colorado Territory.
Rick