Dino Dex First Refactor

Let me know when you have a few minutes.  I want to go over a few of the questions you had which I haven't yet done anything with.
I think I do need the @.  I am getting an error for example in this:

def weight=(new_weight)
    weight = new_weight.to_i
  end

but if I make it @weight it works.  Did I misunderstand?