Explanation

How Day and Night Happen
The sun seems to rise in the morning, crosses the sky during the day and sets at night. However the sun does not actually move around the earth. Earth’s turning on its axis makes it look as if the sun is moves.
The earth makes a complete turn on its axis for 24 hours. It is called as rotation. It causes day and night. The earth also moves around the sun. It takes 365 days or a year. This process is called revolution. The revolution process causes the changes of the season.

Why Summer Daylight is Longer than Winter Daylight
In the summer, the amount of daylight that we get is more than we get in winter. This is not because as much people think we are closer to the sun but because of the tilt of the earth.
The earth is actually closer to the sun in winter than it is in summer but you would be forgiven for thinking that this can not be true after looking out of your window on a cold and frosty morning.
It seems strange that as the earth get closer to the sun during its orbit then the amount of daylight that we get decrease. But that is the case. It is the tilt of the earth that determine the amount of daylight that we get and so the length of time that for us the sun is above the horizon.
(Taken from: www.ictteachers.co.uk)

How Chocolate is made
Have we wondered how we get chocolate from? Well this time we will enter the amazing world of chocolate so we can understand exactly we are eating.
Chocolate starts a tree called cacao tree. This tree grows in equatorial regions, especially in place such as South America, Africa, and Indonesia. The cacao tree produces a fruit about the size of a small pine apple. In side the fruits are the tree’s seeds. They are also known as coco beans.
Next, the beans are fermented for about a week, dried in the sun. After that they are shipped to the chocolate maker. The chocolate maker starts by roasting the beans to bring out the flavour. Different beans from different places have different qualities and flavour. So they are often shorted and blended to produce a distinctive mix.
The next process is winnowing. The roasted beans are winnowed to remove the meat nib of the cacao bean from its shell. Then the nibs are blended. The blended nibs are ground to make it a liquid. The liquid is called chocolate liquor. It tastes bitter.
All seeds contain some amount of fat and cacao beans are not different. However, cacao beans are half fat, which is why the ground nibs from liquid. It is pure bitter chocolate.

How Cancer is Formed
What is cancer? It is actually a group of more than one hundred separate diseases. Most of us are fear from cancer It is reasonable because next to heart disease, cancer is the second leading cause of death.
Cancer cells come from normal cells because of mutations of DNA. Those mutations can occur spontaneously. The mutations may be also induced by other factors such as: nuclear and electromagnetic radiation, viruses, bacteria and fungi, parasites, heat, chemicals in the air, water and food, mechanical cell-level injury, free radicals, evolution and ageing of DNA, etc. All such factors can produce mutations that may start cancer.
Cancer cells are formed continuously in the organism. It is estimated that there are about 10,000 cancer cells at any given time in a healthy person. Why do some result in macroscopic-level cancers and some do not? First, not all damaged cells can multiply and many of them die quickly. Second, those which potentially divide and form cancer are effectively destroyed by the mechanisms available to the immune system. Therefore cancer develops if the immune system is not working properly or the amount of cells produced is too great for the immune system to eliminate.
(Simplified from:www.digital-recordings.com/publ/cancer.html)