(1)
The form of matter can be changed by the increase or decrease of its temperature. For example, water is liquid. But it can be changed into a solid or a gas. In winter, the temperature falls below zero centigrade. The water turns into ice. When the ice is taken into a warm room, it will be changed back into water. When water is heated, it will be changed into vapor.
Solids. Liquids and gases can be changed from one state to another. These changes are called changes of states.
(2)
A farmer who lived in a small village suffered from a severe pain in the chest. This never seemed to get any better. The farmer decided to go to see a doctor in the nearest town. But as he was a miserly person, he thought he would find out what he would have to pay the doctor. He was told that a patient had to pay three pounds for the first visit and one pound for the second visit. The farmer thought about this for a long time, and then he decided to go to the doctor in the town.
(3)
Almost every family buys at least one copy of newspaper every day. Some people subscribe to as many as two or three different newspapers. But why do people read newspapers?
Five hundred years ago, news of important happenings—battles lost and won, kings or rulers overthrown or killed—took months and even years to travel from one country to another. The news passed by word of mouth and was never accurate. Today we can read in our newspapers of important events that occur in faraway countries on the same day they happen.