Tea is the most widely consumed beverage in the world, after water.  It's
good for health, digestion and is a comfort drink for many.  Fortunes have been
made, as in the United Kingdom, and wars fought, as in the American Revolution
(okay, that was taxes, but it was taxed TEA among other things).  China is known
for tea, but other countries (Japan, Vietnam, India) grow the original tea plant
(an evergreen shrub named Camellia sinensis) and every country in the world
consumes tea of one kind or another. 

Different kinds of tea - black, green, herbal, etc, are made preparing the
tea leaves in a different way or using other kinds of flavored plant leaves,
roots or bark.  A good cup of tea depends on the cleanliness of the water, it's
mineral content, the temperature and the time the tea leaves are exposed to it. 
Milk, lemon, spices and other additives combine to make teas distinctive to
time, place and society.

A mug of tea is history in a cup, as well as a science lesson.  It exposes
students to cultures from around the world as they learn about tea traditions. 
http://mentalfloss.com/article/72891/15-tea-traditions-around-world