Repaso prueba global 4o basico

Repaso ciencias prueba global
Unit 7: Changes over time
-Growth and change:
People change constantly, from the day they are born until they die. The most visible changes are those that the body goes through.
-Fast and slow changes:
Besides physical changes, as children grow up, they go through personal changes. These changes are the result of personal life experiences. People learn fromone another, from things that happen to them and from the environment.
Some changes are very slow, like learning to talk. Other changes are very fast, like learning to ride a bike.
-A timeline:
A person’s life story can be represented in a timeline. A timeline shows how time goes by and the changes that take place during that time.
A timeline is similar to a number line used in a Math class. Itis divided into equivalent parts, representing periods of time; for example, a slot for every year in a person’s life.
-Changes in your surroundings:
Just as people change over time, the place where they live also changes.
As changes occur, many things are left behind. They become part of history.

Unit 8: Matter
-Solids:
The shape of solids doesn’t change. They have a fixed shape.Depending on the material they are made of, solids can be harder or softer. Solids have different degrees of hardness. For example, metal solids are harder than wooden or plastic solids.
Solids always take up the same amount of space. This means they have a fixed volume. For this reason, two objects can’t occupy the same space at the same time.
-Liquids:
The most common liquid is water.
Liquids don’thave a fixed shape.
All liquids have one common characteristic: they flow and can be poured from one container to another. This means they take the shape of the container that holds them. Yet, their volume remains the same. That is why liquids have fixed volume.
The volume of a liquid can be measured using a measuring cylinder and is measured in litres (L). For example, a carton of milkcontains one litre (1L) of milk.
-More or less matter:
All liquids and solids are made up of matter. It can be measured with an instrument called a balance.
The amount of matter in an object is its mass. It is measured in grams or kilograms.
-Gases:
You can’t see our touch gases. Gases don’t have a fixed shape.
-Particles:
Everything is made of matter. Therefore, solids, liquids and gases are madeof matter.
Matter is made up of small particles that are invisible to the human eye. These particles are joined together by forces of attraction. (In solids: very strong, in liquids: medium and in gases: weak.)
The closer the particles are to each other, the greater the force of attraction among them.

Unit 9: Changes of state:
-Liquid to gas:
When the sun heats a body of water, the wateron the surface changes state: it turns into water vapour or gas. When water vapour vanishes into the air, water has evaporated.
Evaporation is the change from liquid to gas.
-Gas to liquid:
When someone takes a bath, the walls of the bathroom get damp and the mirror come from water vapour in the bathroom. When the hot vapour touches the cold surface of the mirror, it condenses, changing back toliquid.
Condensation is the change from gas to liquid.
-Liquid to solid:
To make ice cubes, people place a tray with water in the freezer, where liquid water changes into a solid. This process can be observed in nature as well. For example, when rain (water in liquid state) freezes, it becomes into snow (water in solid state). In other words, when water gets really cold, it solidifies.Solidification is the change from liquid to solid.
-Solid to liquid:
When the weather is hot, what happens to the snow? Snow remains on the mountains until heat from the sun melts it. That is to say, snow melts when it is heated.
Melting is the change from liquid to solid.
*Icebergs are a good example of solidification and melting processes. Icebergs are made of fresh water in its solid state....