As you're going on a school trip some of this might not apply, but I'll pass on what we found and hope it helps. I must admit before I start that i hate organised trips and guided tours, so I prioritised quiet reflection over finding out knowledge, my rationale being that I could read up the facts later.
There are 2 camps:
Auschwitz I is very well preserved, it started life as work camp so was well built and planned. It's here that you will see all the hair and spectacles
. The camp is quite small so easy to walk around yourself, but it get jammed with big groups on tours and the israeli groups we encountered were pretty overwhelming, almost aggressive. Understandably they feel they have right to priority in the buildings.
Auschwitz II (Birkenau) is about 2 miles away and is the one the trains arrived in. The sheer size of the place is incredible, and very depressing. it was built by prisoners using poor materials and many huts have fallen down. The water table in this area is very high so when it freezes in affects the foundations (such as they are) causing the collapses. My advice at this site is just to wander round and imagine the terror these poor people felt. Being cold it will be easier to truly imagine the squalor and deprivation inflicted by the Nazi's. We went in the heat of summer with lovely tall meadow grasses around and it was hard to imagine to be fair. Make sure you don't miss the creamatorium and bath house. It's a good long walk from the main gate but this is the bit that most affected me. I'd held it together until we saw the pictorial display examining individual families and contrasted images of the members of each family before the war, and those left after it, with stories explaining what happened to them during the war. Just too sad
I took my then 14 year old daughter and she still discusses what she saw and it has affected her for the better. Few pics I took. I won't say enjoy, but it is a very rewarding trip.
I don't know how to make the pics smaller!!!!
Auschwitz I
Birkenau