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5 About 700 years ago, people started to make
mechanical clocks. At first, they used weights to
power these clocks. The clocks told the hour with
bells. However, the weights were big and heavy, so
these clocks were difficult to move.
6 About 500 years ago, people improved their
clocks. They used springs to power the clocks. The
springs were small and light. So people could move
the clocks easily. Eventually, people began to carry
watches.
[74 words)
In-reading 5 What was the problem with mechanical clocks?
6 To improve the clocks, what did people do?
