A big fun factor in seeing the darkroom at work for the first time (and all other times) is seeing your own image appearing on the paper
So... Let them have fun then!
There are several projects they can do without taking the source images themselves, for example, a photo collage.
Let them expose several images together. Let them make masks with cardboard, and expose different zones of the paper.
You can make some abstract art. This way the pice will be theirs.
You can prepare for example, for a workshop of 10 people some 40 negatives of landscapes and 40 of portraits. They can pick some 4 random landscapes and try to make a scene with them combining the images with 1 portrait from a pile of 4. Or they can go to a collective light table where they choose one portrait and leave the other 30ish they are not currently using.
Give them 2 -3 pieces of black paper and some scissors for them to make masks. Show them to dodge and burn with them, or leave them over the paper.
Or try to add texture to a photo of a face, or texture of a sky on a landscape.
Give them some permanent black markers and let them make blotches of lines and use them to make new masks.
You can also take one portrait of themselves or a loved one!
If you can not take the photo one day prior to the event, let them send a good quality portrait of them and take a photo to be used in the collage!
It does not matter if you need to take the photo out of your screen.
Of course, this needs some planning and testing to give specific guidelines. But I'm sure that this will be more fun than just making one photo of a random thing on the workshop building, even if they pushed the button.
I'm thinking of stuff like this.
That would be a fun darkroom workshop!