Necessity Is the Mother of Invention
Bicycle
Mt. Tambora, a ____ in Indonesia, exploded in 1815.
The explosion created a huge ____ of ash, so crops failed around the world.
As a result, people didn’t ____ enough food to eat.
Surprisingly, this ____ traveling difficult.
Why? In those days, people rode horses, but many horses were ____ for food.
People needed a new way to travel, and Karl von Drais invented the first ____ in Germany in 1817.
Drais’s ____ had two wooden wheels but no pedals.
How did it move ____ pedals?
Well, riders simply ____ the bicycle forward with their feet.
The ____ bicycle is the result of many inventors’ work in the 19th century.
Whiteout
Whiteout was invented by Bette ____.
In 1956, Graham was working at a ____ in Texas, USA.
At that time, people had to retype the ____ page when they made even a small mistake.
Graham was a bad typist, so she needed a ____.
One day, ____ saw some window painters.
____ they made a mistake, they corrected it by simply painting over it.
The next day, she made her own white ____ and used it to correct her typing mistakes.
Surprisingly, nobody ____!
Soon, everybody at the bank began ____ it.
Webcam
The first webcam was invented to watch a ____ pot.
In 1991, Dr. Quentin Stafford-Fraser and Dr. Paul Jardetzky were working at a ____ lab in England.
To work ____, they needed lots of coffee.
However, there was only one coffee machine in the ____.
So, they had to make many disappointing trips to the empty ____ pot.
As a solution, the two researchers ____ up a camera in front of the coffee machine.
The camera took pictures of the coffee pot three ____ a minute.
With ____ software, all the researchers in the building could see the pictures on their local network.
No more ____ trips!