CORRECTIONS: Unit 4: Matter & Unit 5: Electricity and magnetism

NATURAL SCIENCE

Unit 4: matter

Pg.12-13

1. Look at the pictures and answer the questions. 

What differences are there between the eggs?

In picture a the egg is raw (not cooked) but in picture b it is cooked.

Is this a reversible change?

This isn´t a reversible change.

2. Copy and complete the sentences.  

1. Combustion is a chemical reaction.
2. It produces thermal energy, so it´s called an exothermic reaction.
3. One of the ways we use combustion is to heat our homes or to power our vehicles.
4. One of the negative aspects of combustion is carbon dioxide is produced, it contributes to global warming, it produces particles that pollute the air, among others.

Pg.14-15

1. Look at the pictures and answer the questions. 

Which would you prefer to eat? Why?

I would prefer to eat the banana in picture a because it hasn´t oxidised like the one in b.

2. Match to make sentences in your notebook.  

1. In oxidation, atoms lose electrons to oxygen atoms.
2. When iron rusts, it becomes brittle and is easily broken.
3. Fruit that has oxidised turns brown and goes soft.
4. In fermentation, sugar or carbohydrates are transformed.
5. Yogurt is made by adding bacteria to milk.
6. Not all fruit will oxidise when it is cut.

Pg.18-19

1. Copy and complete the sentences. 

1. Physical changes are reversible but chemical changes are irreversible.
2. Homogeneous mixtures have the same color and texture but heterogeneous mixtures have different colors and textures.
3. A solution is a homogeneous mixture that can be separated by evaporation.
4. Distillation is a method of separation that involves evaporation and condensation and dissolution is a method of separation that involves dissolving in water, filtration and evaporation.
5. Combustion is a chemical reaction in which fuel and oxygen combine to produce carbon dioxide, thermal energy, smoke, flames, ash, etc.
6. During fermentation, sugars or carbohydrates are converted into alcohol or acids by yeast or bacteria.
7. Oxidation occurs when electrons are lost to oxygen atoms, for example, when fruit or iron reacts with the oxygen in the air.
8. Reflection occurs when light hits a smooth surface.

5. Copy and complete the mind map.

Unit 5: electricity and magnetism

Pg.20-21

1. Read the text and look at the pictures. Complete the sentence.

Picture a) shows magnetism because there is a

magnet holding the paper to the fridge.

Picture b) shows magnetism because an MRI scanner

uses a magnetic field.

Picture c) shows electricity because the lamp is an

electrical machine.

Picture d) shows electricity because cars use electrical

energy to produce light.

Picture e) shows magnetism because a compass

detects the magnetic north pole.

Picture f) shows electricity because we use a switch to

switch an electric current on and off.

Pg.22-23

1. Describe how these people are using magnetism and electricity.

The people in picture a) are using magnetism to find

their way.

The person in picture b) is using electricity to find

metal objects under the ground.

2. Match to make sentences in your notebook.

a) 5   b) 3   c) 6   d) 2   e) 4   f) 1

Pg.24-25

1. Which of these objects contains a magnet?

Pictures a), c) and d) contain magnets.

2. Copy and complete the sentences in your notebook.

a) Bar magnets can´t be switched on and off.

b) Iron filings can be used to show magnetic fields.

c) A diagram of a magnetic field has lines and arrows to show the direction of the field.

d) When two magnets attract each other, the lines are connected.

e) When two magnets repel each other, the lines don’t join.

f) We can identify a magnet by testing to see if it repels another magnet.

4. What would the magnetic field of this magnet look like?

Pg.26-27

1. Look at the magnetosphere. Where´s the geographical North Pole? Where´s the north pole of the magnetosphere?

 a) The geographical North Pole is in the north – at the 

    top.

b) The north pole of the magnetosphere is at the

geographical South Pole – at the bottom.

2. Correct the false statements in your notebook.

a) False: The Earth’s North Pole isn’t in the same

place as its magnetic north pole.

b) True

c) True

d) True

Pg.28-29

1. Classify the effects of electricity in these pictures: thermal energy or magnetic field.

a) thermal energy b) thermal energy c) magnetic field

2. Copy and complete the sentences in your notebook.

a) Electric current produces thermal energy, a magnetic field and chemical

reactions.

b) We can use the thermal effect of electricity to cook, heat water, dry our hair.

c) Electrolysis is a chemical reaction caused by an electric current/electricity.

d) Electrolysis can be used to electroplate metal objects.

Pg.30-31

2. Match to make sentences in your notebook.

a) 2   b) 4   c) 1   d) 5   e) 6   f) 3

4. In your opinion, which of the inventions in activity 3 needs the most electric current?

The Maglev needs the most electric current because the magnetic force has to lift

and move the entire train.

Pg.34-35

5. Copy and complete the mind map.