I don't think it'll be too hard! I think by the time they get to simulations, they will be getting sick of everything having to follow a predetermined path and look exactly the same every time. I know I'm getting a bit frustrated by it; this animation mode can test your patience!
I think when it comes to that, I'll probably do an example of a trivial, statistically poor PRNG, such as multiplying by 23 and finding the remainder mod 101. Make a list of the first 10 to 15 numbers, and point out that they look fairly random. Maybe even talk about taking just the ones place, and leaving the tens place as RNG state. And then point out that StdGen is the same kind of thing, except better.