random effects model (ANOVA)

hello there,
I am struggling with the following question:

"show that the error SS, for the random effects model, is the same result as for the fixed model".

I am quite confused!!! Firstly, I dont even know what the random effects model should like. I am told that the treatments are random variables rather than fixed. However, I cannot understand how this affects the model.

I can see how the error SS has been obtained for the fixed model , which is
sum(from i =1,....,k)sum(from j=1,....,n)(Yij - Y'bar'i.)^2 which is equal to

sum(from i =1,....,k)sum(from j=1,....,n)(eij - e'bar'i. )^2

which is distributed with a distribution of 'sigma squared * chi-squared with nk - k degerees of freedom.'

I am desperate for help. thank you for your time.