Hello! Do you like beer?
Depends on the beer. Since it is one the oldest beverages humans have produced, it must be good!
Is it really!? How old are we talking?
It goes back at least to the 5th millennium BC in Iran. 
Fascinating. Do you know how they figured out how to make it?
Not exactly, but nearly every civilization has figured out how to brew beer. 
It must be relatively simple then. Are there many steps involved?
It uses cereal grains and the starch sugars produce ethanol and carbonation that results in beer.
What role does yeast play?
They steep a starch, like cereal, in water and then ferment that with the yeast.