Glass is a material that we use every day, but have you ever wondered where it comes from? According to an old story, glass was discovered by accident thousands of years ago. Ancient sailors landed their ship on a beach to cook a meal. They did not have any stones to support their cooking pots, so they used blocks of soda from their cargo.

The fire they made was extremely hot. ( 1 ) _______, the blocks of soda melted and mixed with the sand on the beach. When the mixture cooled down, it turned into hard, clear glass. For many centuries after this discovery, making glass was a slow and difficult process. It was very expensive, so only rich people could afford to buy glass bottles and cups.

( 2 ) _______, in the first century BC, a new technique called "glassblowing" was invented. This allowed people to shape hot glass by blowing air into it through a tube. This method was much faster and cheaper. Soon, glass containers began to ( 3 ) _______ expensive clay pottery, and glass became a common item in homes around the world.

Glass is a material that we use every day, but have you ever wondered where it comes from? According to an old story, glass was discovered by accident thousands of years ago. Ancient sailors landed their ship on a beach to cook a meal. They did not have any stones to support their cooking pots, so they used blocks of soda from their cargo.

The fire they made was extremely hot. ( 1 ) _______, the blocks of soda melted and mixed with the sand on the beach. When the mixture cooled down, it turned into hard, clear glass. For many centuries after this discovery, making glass was a slow and difficult process. It was very expensive, so only rich people could afford to buy glass bottles and cups.

( 2 ) _______, in the first century BC, a new technique called "glassblowing" was invented. This allowed people to shape hot glass by blowing air into it through a tube. This method was much faster and cheaper. Soon, glass containers began to ( 3 ) _______ expensive clay pottery, and glass became a common item in homes around the world.