Necessity Is the Mother of Invention
Bicycle
Mt. Tambora, a volcano in Indonesia, exploded in ____.
The explosion created a huge cloud of ash, so crops ____ around the world.
As a result, people didn’t ____ enough food to eat.
Surprisingly, this made traveling ____.
Why? In ____ days, people rode horses, but many horses were killed for food.
People ____ a new way to travel, and Karl von Drais invented the first bicycle in Germany in 1817.
Drais’s ____ had two wooden wheels but no pedals.
How did it ____ without pedals?
Well, riders ____ pushed the bicycle forward with their feet.
The present-day ____ is the result of many inventors’ work in the 19th century.
Whiteout
Whiteout was invented by ____ Graham.
In 1956, Graham was ____ at a bank in Texas, USA.
At that time, people had to retype the whole page when they made even a small ____.
Graham was a bad typist, so she needed a ____.
One day, ____ saw some window painters.
When they ____ a mistake, they corrected it by simply painting over it.
The next day, she made her own white paint and used it to ____ her typing mistakes.
Surprisingly, ____ noticed!
Soon, everybody at the bank ____ using it.
Webcam
The first ____ was invented to watch a coffee pot.
In 1991, Dr. Quentin ____ and Dr. Paul Jardetzky were working at a computer lab in England.
To work better, they needed ____ of coffee.
However, there was only one coffee ____ in the building.
So, they had to make many disappointing trips to the ____ coffee pot.
As a solution, the two researchers ____ up a camera in front of the coffee machine.
The ____ took pictures of the coffee pot three times a minute.
With special software, all the ____ in the building could see the pictures on their local network.
No ____ disappointing trips!