Science CPE 2015 Examiners’ Report - mes.intnet.mumes.intnet.mu/English/Documents/Examinations/... · Science CPE 2015 Examiners’ Report 1 KEY MESSAGES Candidates must be encouraged

CPE 2015 Science Examiners’ Report

Mauritius Examinations Syndicate April 2016

Science CPE 2015 Examiners’ Report

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KEY MESSAGES

Candidates must be encouraged to:

read the instructions and questions carefully;

practice responding to open – ended questions and to write down their

answers;

apply their knowledge to the context set;

give precise answers;

give answers which is directly linked to the question;

refrain from giving vague answers;

understand the concept of scientific methods

understand and use the correct scientific vocabulary and terminologies

where applicable.


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GENERAL COMMENTS

The pass rate for school candidates in the Science CPE 2015 paper was 73.7 %

which is lower by about 2% from 2014. As in previous years, a high number of

candidates were able to achieve the highest grades, A* and A, with fewer

obtaining the grades C – E. At the lower end, there is a difference of about 11%

between boys and girls with more boys scoring a U. At the upper end, the

difference is significantly reduced to only 1% with more girls getting an A*. As it

has been highlighted in previous reports, the underperformance of boys is a

concern which deserves the attention of all stakeholders concerned.

Candidates from all the ability groups were able to score most marks from

Question 2A. The types of questions set were mostly fill-in-the blanks or

matching which were within the reach of most candidates. Throughout the paper,

it was noticed that wherever a one-word answer was expected, candidates were

able to respond with more confidence than for open-ended questions where they

had to express their ideas in a sentence. The difficulty with the language is

recurrent as well as the use of scientific terminologies.

However, some scripts contained precise and concise answers showing that

some candidates mastered both the scientific concepts and the linguistic skills

required. It was interesting to note that some candidates came up with

unexpected answers and were able to apply their knowledge and understanding

to the contexts given in the questions set.

The 2015 Science paper also showed some difficulties that pupils faced with

regard to topics/concepts. For instance, the concept of energy conversion, the

difference between evaporation and condensation or the processes of

germination and photosynthesis were not fully grasped by all.


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Candidates also found it difficult to make the distinction between sources and

uses or between causes and consequences.

As previously reported, it is important that candidates give precise answers which

are directly linked to what is being asked. Sometimes, answers given reflected

either rote learning of particular concepts and styles of questions or a lack of

mastery of the idea or concept being assessed. For instance, for the questions

related to Global Warming or to renewable or non-renewable sources of energy,

answers given were not always pertinent to the questions asked but contained

information which only remotely related to the topics being assessed.

Some candidates continued to read the questions superficially and to answer

without thinking carefully. Questions set are often within a particular context and

answers given are expected to take into consideration the context given.

As in the past years, language was a major hurdle for many candidates. Although

most candidates were able to read the questions with understanding, some could

not express themselves properly in writing. This difficulty often resulted in

answers which were not precise enough to deserve full marks.

Candidates faced difficulties in questions related to scientific methodology.

Though the question set, Question 4 – 1(a), was relatively basic, many

candidates could not differentiate between the idea of testing or carrying out an

investigation from the expected results of this investigation.

To help pupils perform better and to like Science, the teaching of Science should

be more explorative, with hands-on activities, simple experiments, formulation

and the testing of simple hypotheses, deductive and inductive reasoning. Based

on their previous knowledge, pupils must be encouraged to formulate hypotheses

which they can test. They should be aware of the basis of scientific testing where

only one variant must be manipulated and that it is important to have a control in

all experiment. They should be encouraged to explain the results they obtain


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whether these were expected or unexpected. All the above should be dealt with

bearing in mind the level of the pupils and the topics and concepts in their

syllabus.

SPECIFIC COMMENTS

Section A

Section A comprised Question 1 and Questions 2A and 2B. The items focused

on the Essential Learning Competencies. It carried 60% of the total marks of the

question paper. The mean mark in Section A was 36.7

A number of the items required only a one word answer or were of the fixed item

response type. Candidates were able to score more marks on these items. They

faced more difficulties to answer some of the items which required longer

responses.

QUESTION 1

This question comprised 10 multiple choice items covering the different topics in

the syllabus.

Items: 1, 2 and 5 were found to be relatively easy by most candidates with more

than 75 % obtaining the correct answer:

The following items proved to be more challenging:

Item 3 Through which one of the following processes does water vapour

turn into rain?

A significant number of candidates opted for the wrong answer ‘evaporation’.


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Pupils have not mastered the concepts of ‘evaporation’ and ‘condensation’.

These

are basic scientific concepts which pupils experience in their everyday life. It is

important that they understand the process and not merely try to remember the

words and their corresponding definitions by heart.

Item 4 Which one of the following conditions is necessary for coral polyps to

grow?

The three distractors were chosen by candidates but the most popular distractor

was ‘Shallow, warm and freshwater’. Candidates did not read the different

options given with enough attention.

Item 6 Which one of the following is the source of energy in an electric

circuit?

The word ‘source’ was not understood by some candidates who opted for one of

the wrong answers. Besides knowing the components making up an electric

circuit, pupils must also understand the functions of each of these components in

the circuit. For instance, that the source of energy is the dry cell.

Thus, for example, if we have two dry cells rather than one dry cell (of the same

capacity), there will be more energy which will be available in the circuit. This will

cause the light or bulb to shine brighter or a buzzer to ring louder. The bulb or the

buzzer would indicate whether electricity is flowing in a circuit.

The electric wire needs to have a conductor of electricity to allow the flow of

electricity from the source of energy. Since electricity is flowing, to prevent us

from getting electric shocks, the electric wires need to be insulated or covered

with plastic. The switch stops the flow of electricity in or opens the circuit by


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causing a gap in the connection. When this gap is closed, the electric flow will

resume.

Item 7 In which one of the following is chemical energy converted into

electrical energy?

This item was the least well done within the multiple choice questions.

Candidates opted for all the distractors indiscriminately. When we are dealing

with energy conversion, pupils have to know the form of energy from the source

and the conversion of energy that has taken place.

In ‘Movement of the wind in a wind turbine’, the source of energy is the force of

the wind which pupils learn as being movement energy at this level. This energy

is converted into electrical energy. In ‘Falling water in a hydroelectric power

station’, it is again movement energy as it is the force of the falling water which is

converted into electrical energy. When solar panels capture light, the source is

the light energy from the sun which is then converted into electrical energy. While

when bagasse is burnt, chemical energy in the bagasse is converted into

electrical energy which is used in sugar factories mostly.

Item 8 Which one of the following will form a clear solution when mixed with

water?

A number of candidates did not understand the word ‘clear’. It is the concept of a

substrate dissolving in a given solvent that they should understand here as well

as the meaning of a clear solution (which is not necessarily transparent) as

opposed to a solution containing undissolved particles.

Item 9 Animals have different habitats. What is a habitat?

This item was a knowledge question and pupils were expected to know the term

‘habitat’ in the way it is used scientifically. Though the word ‘habitat’ is a word


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which is close to the French or Creole word ‘habiter’ or ‘habitation’, some

candidates did not find the correct answer.

Item 10 Which one of the following food items will cause obesity if eaten in

excess?

A relatively common wrong answer was ‘beans’. Pupils have learnt that pulses

are a source of protein. However, the influence of common experience might

have impacted on this item. For instance, it is a common perception that kidney

beans (gros pois) cause an increase in weight.

QUESTION 2A (20 marks)

As is usually the case, candidates performed relatively well in this question.

Many of the items were of fixed – response type and were within the reach of

most candidates. However, where a simple sentence was required as answer,

some candidates were unable to express themselves.

Part 1: Fill in the blanks

Many candidates, from most ability groups, were able to score full marks in this

part of the question. However, some continue to make mistakes in copying the

given words from the list. Pupils must be encouraged to copy the words exactly

as given in the list.

Candidates found the word ‘gills’ quite easily for the item The………….. of fish

help them to breathe in water.

It was noted, that a few candidates instead of giving ‘fur’ as the answer for the

item The ……………….. of the dog protects it against cold weather, gave ‘hair’ as


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answer. ‘Hair’ was not one of the given words in the list and though it is a correct

answer, candidates must follow the instructions given for the question.

A number of candidates also confused between the words ‘endemic’ and ‘exotic’.

These are scientific terms with which they ought to be familiar. Pupils should be

encouraged to name and be familiar with the classification of different animals

and plants. It is worth having some practical activities on such topics so that

pupils understand the terms better.

Part 2

a) Give one importance of hens to humans.

A number of correct answers were given by candidates which included the ideas

of hens as a source of food or protein and as pets. However, some candidates

did not give a direct importance of hens to humans. Rather, they gave the

characteristics of hens such as ‘Hens lay eggs but humans do not’.

b) Give one way how rare birds are protected in Mauritius.

A number of correct answers were given by candidates. Answers ranged from

the way the rare birds should be conserved to the laws that should be passed

and enforced to ensure that they are not killed and that their habitats are not

destroyed.

However, there were some incomplete answers or answers which were not

exactly related to the Mauritian context, such as, ‘They should be put in caves’.

Other answers did not really respond to the question, for instance, ‘Rare birds

should be saved’. Pupils must also be encouraged to give full answers which

respond exactly to the question and context, for instance it is important not to


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only say ‘Pass laws’ but for example ‘Pass laws to prevent the destruction of

native forests which are their habitats’.

Part 3: Matching

Many pupils were able to do the matching well. They did not have any major

difficulty in this part of the question.

Question 2B

Part 1

Candidates were required to complete a partly filled table by either giving the

sources of different materials, naming the materials obtained from certain

sources or giving the use of the different materials.

(i) Material: Leather

Pupils had to find out from where leather is obtained as well as to give one of its

use. A significant number of students gave plant as the source for leather. It may

be concluded that they confused leather with rubber. This was sometimes

confirmed by the use of the material given, that is, to make car tyres.

For such questions, it is also important that candidates give common sources

and not sources which can considered as exceptions or being rare, such as

leather from lion, cheetah or elephant. These animals are often preserved under

conservation laws and it is not common to use their skin as leather or the use of

leather made from these skins can be confined to only a few countries or regions.

Correct uses given by candidates included the making of clothes such as Jackets

or to make boots for example. Some candidates also gave answers such as ‘To


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make dresses or to make T-shirts’. Though nowadays we can have dresses or

T-shirts made up of different types of material it is important that pupils give

common uses and not the exceptional ones. The examiner must be able to

ascertain beyond any reasonable doubt that the candidates had understood that

concept. The uses made of a particular material will thus depend a lot on the

properties of this material and this knowledge must be conveyed through the

answers given by the candidates.

(ii) Material obtained from sheep

The expected answer for material obtained from sheep was Wool but Leather

was also accepted as a correct answer. Though this item was accessible to most

candidates, a common wrong answer was Cotton. This answer was derived from

the creole use of the word ‘cotton’.

Candidates were able to give the uses made of either wool or leather, depending

on the answers they gave for the first part. Answers such as ‘To make pullovers’

or ‘To make jackets’ were accepted. Here also, it was important that candidates

conveyed their understanding and answers such as ‘To make T-shirts’ did not

exactly show that the pupils understood the specific uses of wool based on the

properties of the material.

(iii) To make aeroplanes

The expected material to make aeroplanes was Aluminium. Answers such as

wood, leather, stainless steel or plastic were not accepted as the aim was to find

the material used for its specific characteristic which is its weight. A number of

candidates found it difficult to write the word Aluminium. Words such as Aiumroll,

Alumion were quite common. As stressed in previous examiners’ reports, it is


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very important that pupils are encouraged to write down their answers and not

only give answers orally.

Candidates were able to give ‘from the earth’ or ‘from the soil’ for the part on

‘material obtained from’. However, many candidates found it difficult to express

themselves in this part of the question. Some candidates for instance wrote only

‘Land’ as answer.

Part 2 – based on a picture showing a boy burning leaf litter from his

garden

a) Which gas is needed for this fire to burn?

A fair number of candidates were able to give the answer ‘Oxygen’. However,

‘Carbon dioxide’ was a relatively common wrong answer. Pupils must also be

able to make the distinction between a particular gas such as oxygen from air.

b) The fire is giving out smoke. Explain how this form of air pollution affects

plants.

Wherever candidates had to express their answers in a relatively longer

sentence or phrase, they experienced some difficulties. A number of incomplete

answers were obtained or answers which did not fully respond to the question.

For instance, answers such as ‘Plants absorb air pollution’ or ‘Plants breathe

dust in the air’ did not explain how the air pollution is affecting plants. When the

question required an explanation to be given, only the observation based on the

phenomenon or the causes would not be enough to score full marks. The effects

of the causes have to be given as well.


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However, some complete and praiseworthy answers were also obtained such as

‘By blocking the pores of the leaves thus it cannot breathe and manufacture

its food’.

c) Give one way how the boy can extinguish this fire.

A number of candidates came up with correct answers which related to their own

experience and were answers which were not necessarily drawn from their

textbook. It is encouraging that pupils were able to understand the concept of a

fire deprived of a supply of oxygen will eventually die out. Answers such as

‘Throwing rocksand on it’ or ‘The boy must cut out the supply of oxygen by

throwing a wet blanket of it’ were therefore fully credited.

This item also required that the answer carried a small description of what

needed to be done to extinguish the fire. An answer such as ‘Water’ only was

not considered enough to be accepted as a fully correct answer.

d) Instead of burning the garbage, what beneficial use could the boy make of

it?

For this item also, it was expected that answers are not limited to one word only

such as Compost. A number of candidates gave fully correct answers such as

‘He can bury it as it will fertilise the land’ or ‘Bury it to make compost’.


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SECTION B

Section B consisted of two questions, questions 3 and 4 each with different sub

parts. Questions from Section B assessed mostly the Desirable Learning

Competencies. Candidates from all the ability groups should be encouraged to

attempt all the questions as a number of items are within the reach of most

pupils. Usually, items within a question are graded so as to build up confidence in

the candidates when they tackle the tasks. Candidates scored a mean mark of

17 over 40 in Section B.

Part 1

a) A green potted plant which is regularly watered is placed in a dark room.

(i) Give one factor which is absent from the room, thus preventing the

plant from making its own food.

A significant number of candidates gave the correct answer Light or Sunlight.

Some candidates did not read the first part of the question carefully and gave

‘carbon dioxide’ as answer.

Pupils’ attention should be drawn to the words which are in bold in the question.

These emboldened words are meant to guide the pupils and to draw their

attention on specific steps that they ought to take when responding to questions

set.


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(ii) Which gas is given out by this plant when it is in the dark?

Though a number of candidates gave the correct answer Carbon dioxide, a

number of them also gave ‘oxygen’ as answer. The word carbon dioxide was also

often wrongly spelt.

Pupils often forget or do not really grasp the concept that all living things breathe,

be it animals or plants. In the absence of light, for instance at night, plants

breathe normally as all living things do, taking in oxygen and giving out carbon

dioxide.

b) Give one condition which is necessary for a seed to transform into a new

plant.

Seeds from different plants need different conditions for germination to take

place. For instance, some seeds need high temperatures while others need

alternate freezing and thawing. Some will germinate in a sandy or rocky

substrate while still others would need a fertile soil or to pass through the

intestinal tract of specific animals.

However, the most common conditions necessary for all seeds to germinate are

the right temperature (be it hot or cold or room temperature) and moisture to

soften the seed coat. As all living things, the seeds also need oxygen though

often in very small quantities. It is important that pupils understand this concept.

They can be given the example of seeds which germinate only after forest fires,

for example certain pine seeds, so they can understand the idea of right

temperature. They can also be given the example of seeds which will germinate

on tissue paper or newspaper even, for example beans.


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Pupils must also be able to distinguish between the processes of germination

and photosynthesis. A seed does not have a shoot and thus does not have

leaves. As seeds do not have green leaves, they cannot carry out photosynthesis

and thus do not require light. Therefore, light is not an essential condition for a

seed to germinate.

When only one condition is required, candidates are encouraged to give only one

condition unless they are absolutely confident that all the conditions they are

giving are correct ones. By giving more than one condition, they will not be given

extra marks but if all the conditions they have given are not correct they might

lose marks.

c) Give one reason why plants are important to animals.

Most candidates were able to provide a correct answer to this item. Examples of

correct answers were ‘Plants help maintain the composition of air so animals

can breathe’, ‘Plants provide a source of food to herbivorous animals’ or

‘Plants provide shelter to animals’.

However, it was found that some candidates found it difficult to express

themselves. For instance answers such as ‘Animals can live there’ or ‘She gives

fruits’ show the difficulty that some candidates have to convey their

understanding.

Some answers, though in some cases were accepted, ought to be better

formulated so that the meaning is clear to the examiners. For instance answers

such as ‘Because animals can eat many fruits’ or ‘Plants help them to grow

well’ do not answer directly to the question though it is rather clear what the


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candidates had in mind. Answers such as ‘Animals need plants’ do not give any

reason why the animals need the plants.

d) Explain how plants help to prevent soil erosion.

When candidates are required to ‘explain how’, they need to give a more in depth

answer, describing the process and, often, a couple of words only as answer will

not fully answer the question and would not suffice to get full marks. For this

item, it was expected that the candidates would explain that the roots of the

plants trap the soil and prevent it from being washed away.

Some candidates were able to give a complete answer. The idea of plants

reducing the force of the rain thus preventing the soil from being washed away

was also given by a number of candidates and accepted as a fully correct

answer. However, answers such as ‘They are grown around the coast to

prevent soil erosion’ did not explain how the plants prevented soil erosion. Here

also some candidates had difficulty in expressing themselves and answers such

as ‘It maintain the soil’ or ‘It attract the soil erosion’ were obtained.

It is also important that candidates give full answers and relate the function of the

roots of the plants in preventing soil erosion. Thus, by giving vague answers such

as ‘They are wind breakers’ or ‘hold the soil’, the candidates did not explain

fully how the plants prevent soil erosion.


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Part 2

(a) Carnivores need to have strong canines. Explain why.

The idea of carnivores eating meat or their prey which they have to tear had to

be conveyed. A number of candidates gave answers which, though expressed

differently, were correct. For instance, some of them gave ‘Carnivores need to

have strong canines as they feed on meat which is very difficult to tear’ or

‘They need strong canines to capture and tear their prey’.

However, it was expected that candidates would be able to make the difference

between the functions of the canines which is to tear and that of the molars which

is to crush or grind. Thus answers such as ‘To crush meat’ were not accepted.

This item also required candidates to ‘explain why’, that is, they had to relate the

teeth of the carnivores to their diet. An answer such as ‘Carnivores eat meat’

does not fully explain why strong canines are required. Some candidates also

gave answers such as ‘To crush bones’ which is not the function of the canines.

(b) Give one reason why human babies who are aged less than 8 months do

not need to have molars.

Some candidates were able to relate the diet of an 8 months baby with their

dentition and the types of teeth they have. Answers such as ‘Because they don’t

eat food which must be crushed’ showed that the understanding of the concept

was acquired.


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An answer such as ‘Because they are child only and will have molars later’ did

not convey the understanding of the concept. It also demonstrated that pupils

had difficulty in expressing themselves when they were required to explain.

Some candidates gave incorrect elements in their answer and thus could not be

given marks. For instance, ‘Molars grow only in permanent teeth set but

babies have milk teeth set’ contained a wrong concept.

(c) Give one precaution you must take to protect your teeth from decay.

This was a fairly common type of question and pupils are familiar with the

different ways of protecting the teeth. Correct answers included ‘Brush our teeth

after each meal’, ‘I must stop eating sugary food and drinks’ or ‘visit the

dentist for a dental checkup at least one per year’.

It was found that some candidates had confused the topic of prevention of dental

decay with that for how to avoid obesity or to stay in good health. An answer

such as ‘We must not eat oily food’ was also obtained.

Part 3

a) Write down three food items which will make a balanced meal.

Candidates were expected to give one food item from each of the three food

groups carbohydrates, protein and vitamins and minerals. This was an item that

was accessible to a majority of candidates. Some of them however gave at least

two food items from the same food group. Some candidates gave the names of

the food groups instead of that of the food items. The importance of reading the

questions carefully is stressed once again here.


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b) Give one reason why we must store food at low temperature in the

refrigerator.

It was expected that candidates’ answers would include the idea of a slowing

down of activities of microorganisms/ bacteria/ microbes or that these organisms

would not be able to reproduce at low temperatures. As a result, the food would

take longer to decay or rot.

Some candidates had the misconception that low temperatures would kill the

bacteria or microorganism. Others only gave answers such as ‘cold

temperature’. Some pupils also had difficulty in conveying their ideas because of

limited linguistic skills and answers such as ‘microbes can slowly multiply’ or ‘to

be able to eat it next time’ were obtained.

Question 4

Part 1 – This question was based on an experiment involving two potted plants

which were being watered using two different types of water, plant A with fresh

water and plant B with water from a river containing detergents.

a) What is this experiment testing?

While a number of candidates were able to give the idea that it was an

investigation being carried out to find out what will happen to the plants under the

given conditions, many others gave the outcome or the expected results of the

experiment. Correct answers included ‘If the water containing detergents is

better than the fresh water’ or ‘if the plants can survive with polluted

water’. Answers such as ‘We can water plants from fresh water and not with


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water coming from rivers’ or ‘that experiment shows that with polluted

water plants cannot grow well’ did not answer the question.

This item was quite revealing in terms of the understanding that pupils have at

this level on scientific methodologies. Inquiry skills are the basis of Science

learning and without these skills, Science is often perceived as the rote learning

of a series of facts, science vocabulary and theories.

It is important that pupils be initiated to the scientific methodology consisting of

systematic observation, formulation of hypotheses, measurement,

experimentation, testing, and modification of hypotheses and drawing

conclusions. They must be encouraged to understand the difference between

testing a hypothesis from the results obtained. They must also be able to

distinguish between the observations made or results obtained from the

interpretation of results. It is expected that at this level, the teaching of these

skills is done for simple experiments linked to the concepts that they have to

understand within their syllabus.

b) What will happen to plant A and plant B after a few weeks under the same

conditions as at the beginning of the experiment?

Candidates found this item within their reach and many gave the correct

answers. From the experiment, the expected results were that plant A would

grow healthily while plant B would be affected by the polluted water and would

wither or die.


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c) Give one way how polluted water can be purified.

In this item, polluted water referred to any type of pollutants, whether solid,

chemical or organic. Thus answers such as ‘We must boil the water for more

than 15 minutes’ or ‘Filter the water and add chlorine to it’ were both

accepted as correct.

Part 2

a) Give one way how plastic bags harmed the environment in Rodrigues.

Though candidates sometimes had difficulty in expressing their ideas, a range of

correct answers were obtained. The answers given were often linked to real life

experiences. Answers such as ‘They clog drains or rivers’ or ‘they polluted the

environment as they are not biodegradable’ or ‘Since they do not degrade,

they are an eyesore’ were all credited with full marks.

It was however noticed that a number of candidates confused the concept of

rusting with that of non-biodegradable. Some candidates’ answers did not refer to

the harm being caused to the environment but instead to other ideas such as ‘It

may cause severe burns when melted’. Though this is true, it did not answer the

question.

b) Explain how the use of fossil fuels contributes to Global warming.

Few candidates were able to score full marks on this item. Answers often

referred to the consequences of Global Warming instead of how it is caused. It

was expected that candidates would write about the release of toxic gases,

namely carbon dioxide when fossil fuels are burnt and that these gases would


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contribute to Global warming. These gases are part of the greenhouse gases

which when trapped in the atmosphere contributes in making the Earth warmer.

Answers such as ‘When mixed with rain it causes acid rain’ or ‘it causes

pollution’ did not explain how the fossil fuels are contributing to Global Warming

but referred to the other harmful effects of the burning of fossil fuels.

c) Give one way how the consequences of Global Warming affect people’s

lives.

For this item, it was expected that the consequences of Global Warming would

be given and a range of answers were possible. Correct answers from

candidates included ‘because of the melting of ice caps’, ‘people living in

coastal regions may die’ or ‘Global Warming causes severe droughts in some

countries’.

Some answers did not give a consequence but only reiterated what was already

said in the question, that is, people’s lives would be affected. Other answers

were too vague, for example ‘It damages the Earth’.

Part 3

a) Explain why it is better to use light from the sun rather than fossil fuels to

produce energy.

The main ideas expected were either that the sun is a renewable source energy

while fossil fuels will run out one day or that production of energy from the sun

does not cause pollution as the burning of fossil fuels to produce energy. The


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idea of solar energy being less expensive in the long term as compared to fossil

fuel was also accepted.

Many candidates were able to give one or more of these ideas. Those whose

answers included the idea of cost were expected to give the correct explanation

and not only ‘It is cheap’ or ‘It is expensive’. Pupils must be encouraged to give

precise answers and not to answer in a vague way. For instance, for this item, it

would have been better had they indicated solar energy or energy from fossil fuel

when referring to the different sources instead of writing ‘it’. They must also be

encouraged to give more details on how this source of energy is cheap or

expensive (for instance in the short term or long term or as compared to other

sources of energy) or how it is free (for instance, in the long term, there is no

investment to be made).

b) Explain what is the difference between a renewable and a non-renewable

source of energy.

The idea of a renewable source energy being always available while a non –

renewable source of energy would run out one day is sometimes difficult for

pupils to grasp. Though some candidates were able to find the correct answer, a

common wrong answer was that renewable sources of energy do not cause

pollution whereas non-renewable sources of energy cause pollution.

It is important for pupils to make the distinction between these two concepts. We

can have, for instance, renewable but polluting sources of energy such as

bagasse or charcoal or non- renewable and less polluting sources of energy such

as natural gas. Nuclear energy on the other hand can be considered as non-

renewable. Although it causes less air pollution than the burning of fossil fuels, it

can cause different types of pollution on a larger scale and with more devastating

consequences.


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c) Although charcoal is a renewable source of energy, it is not commonly

used. Explain why.

This was an item where candidates were required to use their logical thinking

and it was pleasant to see that a range of correct answers were obtained. Some

candidates had even mentioned the idea of charcoal having a lesser energy

content than some other sources of energy. More common correct answers

carried the idea that the burning of charcoal causes pollution or that charcoal is

made from trees. Consequently a large number of trees have to be cut to make

charcoal which is harmful to the environment.