How Are Stained Glass Windows Made?
How Are Stained Glass Windows Made? In a church you often see windows decorated with colorful pictures and designs. The windows are made of many pieces of colored...
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What Is a Sand Dollar?
What Is a Sand Dollar? Have you ever taken a walk along the beach to collect seashells and found a gray disk shaped like a silver dollar? If so, chances are you found...
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How Does a Cylinder Lock and Key Work?
How Does a Cylinder Lock and Key Work? A cylinder lock is made up of a revolving metal cylinder. Five small pins fall down into the cylinder when it is locked. There...
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What Are QR Codes and How Do They Work?
What Are QR Codes and How Do They Work? A QR code, which stands for Quick Response code, is the trademark of a specific type of two-dimensional bar code that was...
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What Is a Watermark?
A watermark is an identifying image or pattern in paper which is very useful in the examination of paper as it can be used for dating, identifying sizes, mill...
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