Classic Glass Problem

One day in philosophy class they spent a great deal of time debating
whether the glass was half full or half empty. After the class, one
student was feeling pretty good about himself and what he was learning
at university, so when he went home he tried to continue the discussion
with his family.

With maximum drama, he took a 12 ounce glass from the cupboard and
poured in 6 ounces of water. Then took it into the dining room and
placed it in the middle of the table. He proudly asked his family, "can
anyone tell me whether this glass is half full or half empty?"

Without missing a beat, his grandmother replied, "depends if you're
drinking or pouring."