laugh loud.

John: As for your wages , you'll get 50 $ a week to start off with and after six months you'll get 100 $ a week.
Andy : Thank you very much , sir . I'll come back in six months.

Laugh!

Mary: What's yellow and black with red spots?

John: A leopard measles.

Smile.

Ann: Bob , you remind me of Pete.
Bob: I'm a bit like him.
Ann: Oh yes , you are. You both owe me 20 $.

Earthquake prediction.

If you were to hazard a guess at when and where the next major earthquake will strike , there's a chance that you'd be almost as accurate as the experts . The science of earthquake prediction is still in its infancy , which in uncomfortable , considering the threat posed to human civilisation . Even with vast resources at their disposal,often the best scientists can do is say that the odds are that an earthquake will strike where one occurred before . One reason the chances of making an accurate prediction are so low is the the nature of the forces involved. It seems to be impossible to tell the difference between a small earthquake and a warning tremor . Scientists need to decide whether to put lives at risk by not issuing a warning, or constantly issue warnings about the threat of an earthquake that may be ignored. In the end , the odds seem to be against us solving this difficult problem any time soon.

The pencil.

Because the pencil has become such a fundamental part of our lives, it's difficult to remember that people have not been using them forever.Like other products of human ingenuity, pencils had to be invented.
Before the fist half of the sixteenth century , people used to use pens to write with and brushes to paint with . It was also possible to use a metal stick to make faint marks on paper . However, up to that point no one had found an easy way to make marks that could be erased. Then , some time before 1565, a large deposit of chemical, graphite, was found near Borrowdale in Cumbria , England. The locals would use this graphite to mark sheep. Soon , tales of this unusual soft substance had been spread to artists around the world , who were eager to use it to produce works of art.

Graphite is soft and dirty, and in order to write or draw with it, it used to have to be covered in something , such as sheepskin or string. People had been trying to improve the pencil for some time before manufacturers  in Italy came up with the idea of enclosing the graphite in a wooden case . The modern pencil was born.