A fascinating topic. I've given it a lot of thought. First, everyone in the US has been conditioned for 50 years to believe the holohoax. So, you can't 'disprove' it with a few questions or facts. You probably won't be able to 'convince' anyone of anything, and you'll be amazed at the counterarguments that you'll get at every turn. So, don't go in with high expectations.
You don't need to ask any questions. You need to state facts that are irrefutable. So, you'll need documentation. Even with documentation, no fact will be believed, and every fact will be challenged. That's OK, your job is not to 'convince' anyone, it's impossible to overcome years of brainwashing with facts or arguments, instead, your goal is to challenge them and to pique their curiosity and and create an active interest. If you can do that, you've succeeded.
Also, there are two related but separate issues, one, what happened during the war, and two, the holohoax, which is the lies told about what happened during the war. Here is why this is important, many of the holohoax lies are obvious, you don't need to know the history of the war to know that they are lies.
Here is one good example, the USHMM website says that millions of Jews were shipped to extermination centers where they were killed in 'specially developed gassing facilities'. Two hoax gas chambers, one at Auschwitz, and one at Majdanek, are in existence and shown to visitors every day. How do we know that they are fakes without knowing anything at all about WW II? Because both have unbarred plate glass windows that a prisoner about to be gassed could break and escape through. Unbelievable? Apparently not, as visitors see these 'gas chambers' every day and don't laugh at the obvious absurdity of a gas chamber with a window. This shows the incredible power of years of brainwashing. How to document the windows? Show pictures. Will the pictures be challenged? Of course.
Now, showing that these gas chambers are obvious hoaxes has implications. What does is say about the Auschwitz and Majdanek museum directors and staff, about the USHMM, about the whole holohoax establishment. The point is the lies are blatant, obvious. This means that the persons telling them are fools or liars. They are not fools. The phony gas chambers are at the very heart of the holohoax, and they indict the whole holohoax establishment.
Now, there is a web page at
http://www.holohoax101.com that lists and documents many proofs that the holocaust is a hoax. And, there is a flyer that you can print and distribute. If you'll PM me I'll print up the flyers for you to distribute in class and mail them to you. You'll rock their socks, I guarantee.