Lesson 35: Human Limitations

There are limitations to what humans can do.

We cannot hear or see things which are tiny, too soft or well-hidden.
We cannot fly or walk very fast or too far without the aid of technology.


Human are able to overcome their limitations by using devices.
1. We can used telescope, magnifying glass and microscope to 
    see the fine details of an object.
( A )Telescope

( B ) Magnifying glass

( C ) Microscope

2. We can used telephone, megaphone and 
     microphone to speak loud enough for someone.
( A ) Telephone

( B ) Megaphone

( C ) Microphone

3. We used train, car and aeroplane to walk long distance.
( A ) Train

( B ) Aeroplane

( C ) Car

Lesson 34: Development of Technology

Human develop technology for the betterment of mankind. This development has made the world a better and more comfortable place to live in.

1. Technology in Agriculture
A long time ago, simple devices were used to dig holes, and loosen the soil. Later, animals were used to plough the land. 

Today, tractors were used on order to be done more quickly 

2. Technology in Communication 
A long time ago, telegraph and devices such as the telephone allow humans to communicate with each other in far away.

These devices are known as telecommunication technology.

3. Technology in Transportation
Humans have invent a better transport as the technology changes. 

4. Technology in Construction
A long time ago, humans loved in caves and built houses from clay and parts of plants. However, these shelters were not safe. They were not strong and were easily destroyed.

Today, humans are now able to build bigger and taller buildings and most of the houses are built using bricks, concrete and steel which are strong.

Lesson 33: Planets, Planets How Are You?

1. Types of planets

  • Mercury

- It is too close to Sun.
- The temperature is too hot to support life

  • Venus

- A great amount of the heat from the Sun is trapped in its    
- It is hotter than Mercury

  • Earth

-It has water, air and a suitable temperature to support life.

  • Mars

- Almost all of its water is frozen.
- Scientists have not found any life there.

  • Jupiter

- It is so big that all the others planets could fit inside it.

  • Saturn

- It has three wide rings
- There can be seen with a telescope

  • Uranus

-Uranus is lying on its side as it goes round the Sun.

  • Neptune

- It is covered with a blue ocean of liquid methane.

  • Pluto 

- Pluto is very cold because it is very far from the Sun.

2. Inner planets-Mercury, Venus, Earth and Mars

- All these planets are made of rocks
- Each of the inner planet has an atmosphere and it    
  contains air  
  which suitable for living things to survive.
- The atmosphere of the other inner planets is very thin 
  and poisonous to living things.

3. Outer planets-Jupiter, Saturn, Uranus, Neptune  
    and Pluto

-   They are mainly made of gases. 
-   Their temperature is too cold to support life.

Lesson 32: How far and How Big

Scientists have calculated that the Sun is one hundreds of times the size of Earth. Earth is four times the size of the Moon.

The distance from Earth to the Sun is 400 times the distance from the Earth to the Moon.

Lesson 31: Our Solar System

The sun and the nine planets are part of the Solar System

1. The sun is in the centre of the Solar System

2. Asteroids are huge chunks of rocks that travel around 
    the Sun

3. Meteors are tiny rock which probably come from the asteroid 

4. Comets have long glowing tails.

5. All the nine planets move around the Sun in a large oval path.

6. The nine planets are:

  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
  • Pluto 

Lesson 30: Rusting

Iron objects can rust. Therefore, how can you prevent them from rusting?
Difference between a rusted nail and unrusted nail
Rusted nail

- The nail with rusted surface is dull and rough
- When you scrap it off, the rusted surface will blister off.

Unrusted nail

-The clean non-rusted surface stays shiny.

There are different ways to prevent iron from rusting. We can keep it away from air and water. This can be done by:
( A ) Spay painting

( B ) Greasing or oiling

( C )Plastic coating

( D ) Tin plating

Lesson 29: Reuse, Reduce and Recycle

Natural and man-made materials are very limited. Therefore, we should reuse, reduce and recycle them.

( A ) We can reuse tins, cans and bottles

( B ) We should try to reduce the use of paper     
         because we have to cut many trees in order to     
         produce papers     

( C ) We should recycle newspapers instead of burn

Lesson 28: Natural and Man-made Materials

Materials are either natural materials or man-made materials. Natural materials are found in nature. Man-made materials are made by man.

( A ) Rubber and silk are natural materials.
For example:  Eraser

( B ) Plastic and synthetic cloth are man-made 
For example: Plastic Bag

Lesson 27: Combined Uses of Materials

Different materials can be used to make an object

( A ) This pair of shoes is made of leather, metal and 

Leather - strong and flexible
                - lasts longer and is comfortable to wear

Metal - strong so that the buckle will not break easily

Rubber - is water roof
                - gives the shoes a good grip on the ground

( B ) Electric plug is made of plastic or porcelain

- Plastic or porcelain are insulators of electricity

- The pins are made of metal because it is a     
   conductor of electricity

( C ) Window is made of glass

- Window is made of glass because glass is transparent

- The window frame is made of metal because is hard and      

Lesson 26: Choose Suitable Materials

We use heat insulators to keep things hot or cold. These heat insulators trap air and therefore, cuts down heat from going through the material.

( A ) Polystyrene material

  • contain trapped air
  • good insulators of heat
  • used to make food containers
( B ) Towel
  • used to wrap hot things to keep them warm
  • used to wrap frozen things to keep them cold