Why is it hard for a program to generate random numbers?

Question

My kids asked me this question and I couldn\'t really give a concise, understandable explanation.

So I\'m hoping someone on SO can.

Answer 1

Ask them to devise a step-by-step method to generate a random number.

And don't accept "pick a number from 1 to 10" as an answer ;)

Trying out a problem should illustrate the difficulty of having to generate random numbers from a set of instructions, just like what computers actually have to do.