Glass is made by heating sand, along with small amounts of other materials, until it melts. The h liquid c then b shaped bef it co and har. Glass obj were alr being ma more th four thousand years ago. About two thousand years ago, craftsmen discovered that they could blow air into melted glass through a long tube. This allowed them to make bottles and cups much more quickly and cheaply.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.