Root Beer

Root beer from a bottle,
root beer from a can,
but root beer from a tub
is how it all began.
Powdered roots and sugar,
cold water and yeast.
These are the ingredients –
the main ones, at least.
Roots give it flavor and foam
but – gee whiz!
It's the yeast and the sugar
that make it fizz-z-z-z-z.