Wounded Knee is a Huge part of Native American history.
You should feel honored to be able to educate your classmates on this topic. Everyone should know about this history.
So there are two main battles at wounded knee.
The first occurred way back in the 1800s. It was a Massacre, a slaughter. What happened in summary: Native people had a new sacred dance brought to them by the profit Wovoka. It was called the "Ghost Dance". By doing this dance Natives hopped to bring back their ancestors, at least in spirit. It was not harmful to the colonizers. But they outlawed the dance because it scared them. At this time Natives did not have religious freedom, that was taken from them by the colonizers/government. Well Natives decided to continue the dance anyway. The soldiers got pissed and scared. They went after Native leaders. Killed one very famous Native leader, Sitting Bull. After that another Native leader tried to bring his people to a safe place. Unfortunately the soldiers came and massacred them. Men, Women, and Children.
The Massacre happened in 1890. The death count between 150-300 (likely on the higher side) for Natives only. Not even half that was deaths of soldier. One count says only 25 soldier deaths.
The second battle at wounded knee, Siege at Wounded Knee, happened during the American Indian Movement. Called AIM. The American Indian Movement was kinda like the Malcom X movement. It was a civil rights movement, not exactly passivist. It was in the 60s-70s mainly. At one point during the movement AIMsters decided to take over wounded knee. Basically to hold up fort there until they could get the government to listen to some of their demands. The government got scared and arrested many Natives for no reason. The Siege was in 1973.
http://www.manataka.org/page1710.html (scroll down it will tell you number of arrested, number shots fired, etc.. it's in black on the left hand side of the page near the bottom)
http://www.essortment.com/all/siegewoundedkn_rmpq.htm
Even today if you visit Wounded Knee (on Lakota land) you will feel the energy of these massacres. It is very sad.
By the way I'm sorry your teach is such a jerk.
Hope this helps. Good Luck on your presentation!