Here are some resources to help teach this in the classroom. It's a topic I think deserves attention by every teacher if they can tackle it. I went through school not even learning about this seminal event in history and I think it is all our duties as teachers to "remember" and bear witness, always.
1. Larry Ferlazzo has a fine reference list of resources.
2. See the attached worksheets and reading lessons.
3. This great book is a must for the classroom, IMHO. Hana's Suitcase.
4. Here is my post about Holocaust Memorial Day.
5. Viktor Frankl's video and this lesson (attached) - Man's Search For Meaning is a very easy lesson for intermediate/advanced level classes.
Night by Elie Weisel is a go to book about the holocaust.
I'd also mention this site of photos of Auschwitz. Students choose and print out 7 photos and make up a story of a person at Auschwitz.
Students might also read one of these biographies of children of the holocaust and give a summary or present to the class.
This documentary really puts a human face on the holocaust. Memorandum. Brought to you by the excellent site of the National Film Board of Canada.