CLEVER CONSUMERS INVESTIGATE DETERGENTS __

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SEGON CICLE

Crèdit variable integrat

Llibre de l’alumnat

Ciències de la naturalesa en anglès

_________________________________________________________________ ____

CLEVER CONSUMERS INVESTIGATE DETERGENTS

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Presentació del crèdit ... 3

List of Activities ... 5

Introduction: Clever Consumers ... 9

Unit 1: Stains ... 17

Unit 2: Dirty and Clean ... 47

Unit 3: Are all Waters the Same? ... 65

Unit 4: Clean Clothes, Dirty Rivers? ... 91

Appendix 1: Laboratory Skills ... 111

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CLEVER CONSUMERS INVESTIGATE DETERGENTS

QUÈ ÉS?

És un crèdit variable integrat de Ciències de la naturalesa en anglès pensat per al 2n cicle d'ESO.

OBJECTIUS:

L’alumne, en acabar el crèdit, ha de ser capaç de:

1. Iniciar-se en el plantejament de petites investigacions.

2. Fer una anàlisi de les variables i estudiar el procés de la neteja de la roba.

3. Comparar alguns detergents i el seu efecte en el medi ambient.

4. Valorar críticament el rol de les persones com a consumidors.

5 Comprendre i produir missatges escrits i orals en anglès.

COM?

Els alumnes d'aquest crèdit variable formeu part d'una organització de consumidors anomenada "Clever Consumers". Pertanyeu a uns equips

d'investigadors (“research teams”) que atenen els problemes i qüestions que els hi adrecen els consumidors. Les consultes dels consumidors poden ser de tipus pràctic o bé teòric.

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LIST OF ACTIVITIES

INTRODUCTION: CLEVER CONSUMERS

What do you know about consumer organizations? Fact File 1: What are consumer organizations? UNIT 1: STAINS

What do you know about planning an investigation?

Consumers want to know

1. A letter from students from Sant Vicenç del Munt 2. A memorandum

3. A memo for you from “Clever Consumers”

Let's investigate: A/ Identify the problem B/ Design the investigation Fact File 2: Controlled Variables C/ Do the experiments

D/ Observe and record the results E/ Draw conclusions

“Clever Consumers” respond

Fact File 3: Factors which influence the cleaning power of detergents

Self-assessment

UNIT 2: DIRTY AND CLEAN

What do you know about cleaning?

1. A cartoon strip: A day in the life of Marc Rovira 2. A telephone message

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Self-assessment

UNIT 3: ARE ALL WATERS THE SAME?

What do you know about water?

Consumers want to know 1. Isidro Cuesta’s letter 2. A brief summary 3. A memo

Let's investigate: A/ Identify the problem B/ Design the investigation Fact File 1: Hard water

Field Work 1: Detergent labels C/ Do the experiments

D/ Observe and record the results E/ Draw conclusions

Self-assessment

UNIT 4: CLEAN CLOTHES, DIRTY RIVERS?

What do you know about detergents?

1. An interview with Maria Puig, the mayoress of Sant Vicenç del Munt 2. A memo from “Clever Consumers”

Let's find out:

A/ Identify the problem B/ Look for information

Fact File 1: The most common ingredients in detergents Fact File 2: Characteristics of biological detergents

Field Work 1: A comparative analysis of concentrated washing powders Fact File 3: Where do the detergents you use at home go?

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APPENDIX 1: LABORATORY SKILLS

Lab Skills File 1: Què és el que saps sobre planificar i realitzar una investigació? Lab Skills File 2: Becoming a young scientist (a Clever Consumer’s diary)

Lab Skills File 3: Laboratory roles

Lab Skills File 4: In your research team, who does what?

Lab Skills File 5: Becoming familiar with laboratory equipment in English Lab Skills File 6: How to use an electronic balance

Lab Skills File 7: How to use a measuring cylinder Lab Skills File 8: Laboratory rules

Lab Skills File 9: Self-assessment on lab skills

APPENDIX 2: PROJECTS

Project 1: Washing Survey

Project 2: I wash, you wash, he washes...

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INTRODUCTION

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WHAT DO YOU KNOW ABOUT CONSUMER ORGANIZATIONS?

Read the following sentences and decide which is the best answer: A, B or C.

1. Consumers are the people who .... a) consume drugs.

b) buy products or pay for a service. c) watch commercials on TV.

2. We live in a consumer society. This means that ... a) we need to buy products all the time.

b) this society consumes us. c) everybody sells things.

3. A consumer organization is an association of people who ...

a) compare products and services and informs consumers about them. b) criticize the companies that make products.

c) sell products or have a shop.

4. A consumer organization is formed by a team of ... a) expert scientists, technicians, lawyers, etc. b) consumers.

c) advertisers.

5. Consumer organizations are ... a) part of a country’s government.

b) independent. They do not work for any particular company, political party, or advertising agency.

c) part of a company that makes a product.

6. The first consumer organizations in Spain were formed in the ... a) 1960s.

b) 1970s. c) 1980s

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FACT FILE 1: What are consumer organizations?

We often describe our society as a consumer society. But what does this mean? Who is a consumer and what does a consumer do? Answer this questionnaire to find out.

QUESTIONS ANSWERS

1. Have you bought anything this week (a magazine, a

pullover, a bottle of shampoo)? YES NO

2. What did you buy?

3. Where did you buy it (supermarket, shop)?

4. How much did it cost? ... ptes.

5. Are you satisfied with it? YES NO

When you buy products, you participate in our consumer society. You are a consumer. Some consumers think carefully before they buy products. They

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by Jim Davis, adapted from “Gardfield”.

However, consumers cannot investigate all aspects of a product before they buy it. But there are organizations that can do this. They are called consumer

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information is independent because consumer organizations only test products for consumers. They do not do any work for companies or governments.

Consumer organizations publish the results of their research in consumer

magazines. Consumers can read these magazines and receive information about all sorts of products and services from cars to hospitals, from washing powders to hairdressing salons. In Spain, for example, we have “Ciudadanos”, “OCU

-Compra Maestra”, etc.

Sometimes consumers contact consumer organizations directly when they have questions or problems.

Let’s imagine that you belong to a consumer organization called “Clever Consumers”. This organization helps consumers in two ways:

1. “Clever Consumers” gives consumers information and advice about the products they can buy.

2. “Clever Consumers” investigates products for consumers.

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FACTFILE 1 EXCERCISES

1.

Before reading this fact file, you answered the questionnaire in the section “What do you know about consumer organizations?”. Now check your answers.

2.

These people work for a consumer organization. But what are their jobs? Match each letter (column 1) with the corresponding number (column 2).

a) lawyers

b) scientists

c) technicians and engineers

d) secretaries

e) reporters

1. carry out some investigations to analyse the composition and quality of different products in the market.

2. publish reports with the results of the comparative analysis of the products in magazines like “Ciudadanos”; “OCU-Compra Maestra”, etc.

3. assess on legal aspects.

4. assess on technical aspects, test how

effectively different machines and apparatus work, the strength of the materials, etc.

5. read the consumers’ letters and write memorandum, answer the telephone, etc.

3.

Here are the titles of some consumer magazines. Try to match the title with the name of the country of the consumer organization that publishes it.

MAGAZINE COUNTRY

a) Consumer Reports

b) Ciudadanos

c) Que Choisir

1. Netherlands

2. Great Britain

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UNIT 1

STAINS

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WHAT DO YOU KNOW ABOUT PLANNING AN INVESTIGATION?

1. The first step to plan a scientific investigation is to set the question you have to investigate, i.e. to identify the problem.

TRUE FALSE DON’T KNOW

2. You must decide the steps of your investigation before you begin the experiment in the laboratory.

3. You select the appropriate laboratory equipment at the same time that you do the experiment in the laboratory.

4. An independent variable are all the factors in an investigation which you have to keep the same in the two experiments, if you want the results of these experiments to be scientific.

5. You observe the results, but it is not necessary to write them down in your notebook. You can remember them.

6. You write the conclusions of your investigation by using your observations and experiences during the investigation.

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CONSUMERS WANT TO KNOW

1

. A LETTER FROM STUDENTS FROM SANT VICENÇ DEL MUNT

This is one of the letters "Clever Consumers" has received. In the letter you will find the first problem you have to investigate. Read the letter and answer all the questions.

a) Who is the letter from?

b) Where do the students live?

c) What problem has Sant Vicenç del Munt got?

d) What is the cause of the problem in Sant Vicenç del Munt?

e) What do the students from Escola Mestral want to know?

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C/ Montseny, 23

17401 Sant Vicenç del Munt Girona

25 September 1998

CLEVER CONSUMERS C/ Roger de Llúria, 64 08009 Barcelona

Dear Sir or Madam,

We read about your consumer organization in "El Periódico de l'Estudiant" and we hope you can help us.

We are a group of students in the third year of ESO at the Escola Mestral in Sant Vicenç del Munt, Girona. There is a little lake near our village. Our parents went fishing there when they were students, but now there are no fish in the lake. Our teacher explained to us that some ingredients in detergents slowly killed the fish.

In our local supermarket, they sell some detergents that are called "biological". We would like to know if these "biological" detergents eliminate common stains (for example, coffee, orange juice or oil stains) better than a "non-biological" detergent. Why? Because we would like to convince our parents to buy and use "biological" detergents.

Please investigate and tell us which detergent eliminates stains better, a "biological" detergent or a "non-biological" detergent.

Thank you for your attention and we look forward to hearing from you soon.

Yours faithfully,

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2.

A MEMORANDUM

Your consumer organization “Clever Consumers” is very efficient and

well-organized. Every time they receive a message from a consumer, they complete a “memorandum” or “memo” and put it in the file.

You have just received a letter from the students from Escola Mestral. Complete the “memo”.

CLEVER CONSUMERS MEMORANDUM

TO:

FROM:

DATE:

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3.

A MEMO FOR YOU FROM CLEVER CONSUMERS

Your RESEARCH TEAM receives this memo from your consumer organization, “Clever Consumer”. Read it carefully, and underline the question you have to investigate.

CLEVER CONSUMERS MEMORANDUM

TO: All members of “Clever Consumers”

FROM: the secretary

DATE: 4th October 1998

SUBJECT:

There is a meeting tomorrow afternoon at 4.00 p.m. to plan an investigation. The students from Escola Mestral want to know if biological detergents eliminate coffee stains, oil stains and orange juice stains as well as non-biological

detergents do. We must plan an investigation to answer the students’ question. Come to the meeting with ideas about the investigation. Make a list or draw the things you would do to solve this problem.

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LET’S INVESTIGATE

A/ IDENTIFY THE PROBLEM

You belong to the consumer organization Clever Consumers. You are a group of researchers who plan investigations to test different products.

Your RESEARCH TEAM has to investigate the question the students from Escola Mestral have. Look at the letter again.

What do the students want to know? Copy the question from the letter.

You have to investigate "Which ... ... ...?"

B/ DESIGN THE INVESTIGATION

In this section your RESEARCH TEAM has to plan an investigation to answer the question from the students from Sant Vicenç del Munt.

1.

THINK ABOUT WHAT TO DO

1.1. What do you have to do to find the answer to the question?

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1.3. These pictures represent the actions you have to do. Put them in chronological order.

Put the two detergents into water Observe changes

Stir the detergent in water Cut a cloth into pieces

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2.

IDENTIFY THE VARIABLES TO BE CONTROLLED

2.1. Compare these two experiments and answer the questions below.

To answer the question "Which detergent removes stains of coffee, orange juice or oil better, a biological or a non-biological detergent?" you have to compare the cleaning powers of two different detergents, detergent A is biological and detergent B is non-biological.

EXPERIMENT 1 EXPERIMENT 2

DETERGENT A DETERGENT B

a) What is different in the two experiments?

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2.2. Read and think.

1. a) If you wash "cloth A" with a coffee stain with 1 g of "detergent A" and "cloth B" with the same stain with 5 g of "detergent B", will the result of your experiment be exactly the same?

b) Why?

c) Consequently, one factor you have to control so that the results of your experiment are reliable* is the ... of ...

2. a) If you wash "cloth A" with a coffee stain in 1 l of water and "cloth B" with the same stain in 100 ml of water, will the result of your experiment be exactly the same?

b) Why?

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4. a) If you put "cloth A" with a coffee stain in water with "detergent A" and leave it there for 10 minutes, and "cloth B" with the same stain in water with "detergent B" and leave it there for 60 minutes, will the result of your experiment be exactly the same?

b) Why?

5. a) If you wash "cloth A" with a coffee stain with "detergent A" and the water is at room temperature, and "cloth B" with the same stain with "detergent B" and the water is at 60 ºC, will the result of your

experiment be exactly the same?

b) Why?

* reliable: fiable

CONCLUSION

a) Which factors do you have to control to do your experiment?

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FACT FILE 2: Controlled or independent variable

All the factors in an investigation which can vary and consequently, affect the results are called VARIABLES.

The factors you have to keep the same when doing the experiment so that the results are reliable* are called CONTROLLED VARIABLES or

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3.

CHOOSE APPROPRIATE LABORATORY EQUIPMENT

What do you need to do your experiments? Look at these pictures and tick only the necessary materials.

LABORATORY EQUIPMENT

beaker Erlenmeyer flat-bottomed funnel flask flask

(conical flask)

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Petri dish test test tube measuring tube rack cylinder

thermometer stopclock mortar stirring or timer rod

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4.

DECIDE HOW TO CONTROL THE VARIABLES

Fill in this grid.

CONTROLLED VARIABLES

HOW MUCH? HOW LONG? WHAT TEMPERATURE? LABORATORY EQUIPMENT FOR MEASURING 1. 2. 3. 4. 5.

Congratulations! Now you have defined all the aspects of your investigation. Stop here and compare your data with the other students in class.

5.

DEFINE ALL THE INVESTIGATION IN DETAIL

What will you do in the laboratory? Write all the things to do on the next page. You have to mention every single action with all the details and draw a picture of each step.

If you have vocabulary problems with the instructions, look for the words you need in the previous exercises.

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CLEVER CONSUMERS INVESTIGATION ... Objective:

Material:

Laboratory Equipment:

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C/ DO THE EXPERIMENTS

Now you are at the laboratory. Look at the LABORATORY ROLES from Lab Skills File 3, and decide who will be the INSTRUCTOR and who will be the

RECORDER. Make sure you have the material and all the laboratory equipment you need.

Scientists have to be very observant when they work. That’s why they fill in an observation grid like the one you have on the next page. They take note of all the details they observe while doing the experiments and the problems they have.

HELP

OBSERVATIONS: What things can you observe while doing the two experiments?

If you put the biological detergent and the non-biological detergent into two beakers with water at the same time and stir to dissolve the detergents, you can observe:

1. Which detergent is easier to dissolve?

2. Do the two detergents make a lot of foam?

3. Which detergent makes more foam (bubbles)?

4. What colour does the water get?

5. ...?

How are you going to take note of all this? Design a grid to take note of all these details.

PROBLEMS:

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INVESTIGATION ... : ...

Instructor:... Performer 1: ... Performer 2: ...

Biological detergent: ... Non-biological detergent: ...

OBSERVATIONS:

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D/ OBSERVE AND RECORD THE RESULTS

1. After the experiments, let the cloths dry.Then, look at the stains washed in each

experiment. Examine the quality of each stain and circle the sentence which best describes it.

STAINS BIOLOGICAL NON-BIOLOGICAL coffee the stain is not there.

the stain is very light. the stain is quite intense.

the stain is not there. the stain is very light. the stain is quite intense. orange

juice

the stain is not there. the stain is very light. the stain is quite intense.

the stain is not there. the stain is very light. the stain is quite intense. oil the stain is not there.

the stain is very light. the stain is quite intense.

the stain is not there. the stain is very light. the stain is quite intense.

Do you have any other observations?

2. Mark with a cross "X" the detergent which eliminated these stains better.

KIND OF DETERGENT

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E/ DRAW CONCLUSIONS

1. After comparing the cleaning power of the two detergents, you have to draw

conclusions. Use this model if necessary.

The ... detergent "..."

cleaned/eliminated the ... stain better than the ... detergent "..."

The results of cleaning/eliminating a ... stain with the biological detergent "..."and the non-biological detergent "..." are the same.

If you have other conclusions, write them in these boxes.

2. Now compare your conclusions with your colleagues’ conclusions. Complete

these tables with the results from all the research teams : no stain, a very light stain or a quite intense stain.

Research team 1

biological

... .

non-biological ... .

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Research team 3 biological ... non-biological ... . coffee orange juice oil

Research team 4

biological ... non-biological ... coffee orange juice oil

Research team 5

Research team 6

3. Calculate the percentage in each case.

Final results

biological non-biological coffee ... % no stain

... % a very light stain ... % a quite intense stain

... % no stain

... % a very light stain ... % a quite intense stain orange juice ... % no stain

... % a very light stain ... % a quite intense stain

... % no stain

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4. Analyze the results and draw conclusions.

... detergents cleaned/eliminated the ... stain better than ... detergents.

The results of cleaning/eliminating a ...stain with biological detergents and non-biological detergents are the same.

5. Now it’s time to answer the question made by the students from Sant Vicenç

del Munt “Which detergent removes stains of coffee, orange juice or oil better, a biological or a non-biological detergent?”

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CLEVER CONSUMERS RESPOND

Now you have tested the effects of a biological detergent and a non-biological detergent on coffee, oil and orange juice stains, so it's time to give an answer to the students from Escola Mestral. Complete the following letter with the results of your work and other necessary details.

CLEVER CONSUMERS C/ Roger de Llúria, 64 08009 Barcelona

... 2nd-year ESO students

Escola Mestral ... ...

Dear students,

We are pleased to answer your letter dated ... concerning ...

After our laboratory experiments, our scientists say that ...

...

If you have any further questions, we will be happy to help you, and thank you very much for trusting our organization.

Yours sincerely,

...

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FACT FILE 2: Factors which influence the cleaning power of detergent

Detergents, for example the washing powders you used in your investigation, are chemical products. The chemical substances in a detergent give it its cleaning power. However, there are also some external factors which can increase the washing properties of a detergent. Those were the factors that you had to control when you designed your experiment. They were:

1. the amount of detergent 2. the amount of water 3. the kind of water

4. the amount of dirt on the clothes 5. washing time

6. water temperature

7. different kinds of movements

So when you wash your clothes, remember:

1. When we use more detergent per the same amount of water (100 ml of water and 100 g of detergent versus 100 ml of water and 50 g of detergent) the detergent will wash the clothes better.

2. When the water temperature is high, more detergent can be dissolved in the water. Consequently, the detergent will wash the clothes better. Most detergents are effective in temperatures above 30º. However, the hotter the water, the greater the energy consumption. Remember that the colours of the clothes will also dissolve better in hot water.

3. The longer the time we leave our dirty clothes in water and detergent (five hours versus one hour), the better the stains will dissolve.

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Women scrubbing clothes

FACTFILE 1 EXCERCISES

1.

Read the text. Are the following sentences true or false?

1. Wasing machines scrub clothes. TRUE FALSE 2. Dark-cloured clothes need to be washed in very hot water. TRUE FALSE 3. Heating the water is the most energy-consuming part of the

washing process.

TRUE FALSE

4. You can scrub delicate clothes. TRUE FALSE 5. In most cases, it is easier to wash away grease in hot water than

in cold water.

TRUE FALSE

6. A hundred years ago, people scrubbed their clothes. TRUE FALSE 7. It is not a good idea to soak dirty clothes in water and detergent

before putting them in the washing machine.

TRUE FALSE

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SELF-ASSESSMENT ON SCIENCE SKILLS

Give yourself a mark on each step of your investigation.

DESIGNING YOUR EXPERIMENTS

1. We chose appropriate laboratory equipment. 0 1 2 2. We chose an appropiate amount of detergent. 0 1 2 3. We chose an appropriate amount of water. 0 1 2 4. I wrote all the steps of the experiments in detail 0 1 2 3 4

PERFORMING YOUR EXPERIMENTS

1. To measure the amount of water I used : a) a beaker

b) a measuring cylinder

c) a measuring cylinder and a dropping pipette

0 1 2 2. To measure the amount of detergent I used:

a) the electronic balance

b) the electronic balance and a ... ...

0 1 2 3. To measure the water temperature, I put a

thermometer into the water for 5 minutes. 0 1 2 4. I followed all the steps in the correct order

and at the same time. 0 1 2 5. I worked with the other members of my group

and helped them. 0 1 2 6. I observed carefully and took notes during the

experiments 0 1 2

1. Do you think that the results of your experiments are reliable? 100% reliable

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SELF-ASSESSMENT ON LANGUAGE SKILLS

USE OF ENGLISH

LISTENING

COMPREHENSION

1. I could understand the teachers' oral

instructions and explanations. 0 1 2

READING

COMPREHENSION

2. I could understand all the written instructions

to the exercises. 0 1 2

VOCABULARY 3. I tried to use English to name the laboratory

equipment. 0 1 2

WRITING 4. I could write the diary comments and the

instructions of the experiments in English. 0 1 2

SPEAKING 5. I tried to use English to give all the oral

instructions of the experiment when I was the

instructor. 0 1 2

SPEAKING

.

6. I tried to use English to ask questions to the teachers, ask for things to my classmates and

discuss problems in my group. 0 1 2

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SELF-ASSESSMENT ON ATTITUDES

Think about these aspects and give yourself a mark from 0 to 3.

1. INTEREST 0 1 2 3

2. PARTICIPATION 0 1 2 3

3. ATTENTION IN CLASS 0 1 2 3

4. PERSONAL EFFORT TO USE

ENGLISH IN CLASS 0 1 2 3

5. ORGANIZATION OF DOSSIER 0 1 2 3

6. DIARY 0 1 2 3

7. HOMEWORK 0 1 2 3

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DIRTY AND CLEAN

In this unit you are going to:

CONSUMERS WANT TO KNOW : - read a cartoon strip

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WHAT DO YOU KNOW ABOUT CLEANING?

Read the following sentences and decide if they are TRUE or FALSE. Circle your answer.

1. We only get dirty when we work or play. TRUE FALSE DON'T_KNOW

2. Grease and dust are the main kinds of dirt on our clothes.

TRUE FALSE DON'T KNOW

3. It is easy to clean dirty hands with only water.

4. Surface tension is a property of liquids.

5. It is easy to mix oil with water.

6. Cleaning is a very simple process.

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CONSUMERS WANT TO YOU KNOW

1.

A CARTOON STRIP: A Day in the Life of Marc Rovira.

Marc is going to play football. Oh no, the motorbike has covered him with dust.

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2

. A TELEPHONE MESSAGE FOR "CLEVER CONSUMERS"

2.1. A message was left on the answering machine. Listen to it and complete the following sentences.

Cliqueu sobre aquesta icona

1. ... telephoned "Clever Consumers".

2. He telephoned because he has got a ... for "Clever Consumers".

3. His clothes are always ... and consequently, his mother gets ... with him.

4. His mother says that cleaning his clothes is ...

5. He thinks that cleaning clothes is ...

6. He ... wash his clothes.

7. He wants information about the ... of ... clothes.

8. "Clever Consumers" will send him this information in a ...

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2.2. The following message was left on the answering machine at the office of “Clever Consumers”. Listen to the message carefully first and then complete this form.

TELEPHONE MESSAGE

Message for ...

Received from ...

Date...

Subject:

...

Action to be taken:

...

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3

. A MEMO FROM “CLEVER CONSUMERS”

You receive this memo from your consumer organization, "Clever Consumers". Read it carefully, and underline the information you have to look for.

MEMORANDUM

TO: All members of "Clever Consumers"

FROM: The secretary

DATE: 30 October 1998

SUBJECT:

Last week we received a telephone message from Marc Rovira, a

student at the Escola Mestral. Marc would like some information on

the process of cleaning clothes. Is cleaning a simple process? What

factors are involved in cleaning clothes? Our laboratory chemists

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LET’S FIND OUT

1. This time your RESEARCH TEAM has to answer Marc Rovira’s question. Look at the telephone message and at the memo again. What does Marc want to know? Copy the question here.

You have to find out "... ...?"

B/ LOOK FOR INFORMATION

Here is some information from our laboratory chemists. Read it carefully.

FACT FILE 1: What does cleaning mean?

Cleaning is a process which involves three stages:

1. make the water penetrate the fibres of the cloth.

2. mix grease and dust with water in order to separate the grease and dust from the fibres of the cloth.

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This seems a very simple process because we do it many times every day. But this process is not as simple as it seems.There are two main problems:

1. To make the water penetrate the fibres of the cloth 2. To mix grease with water

1. How to make the water penetrate the fibres of the cloth

Is water good at wetting things? Does water penetrate the fibres of the cloth easily? Let's go to the laboratory and do some practical work on stage one of the cleaning process.

PRACTICAL WORK 1: The wetting action of water

Objective: to compare the wetting power of water alone and water with detergent.

Material: You need: - water - washing powder - a waterproof cloth

Lab equipment: You need: - a spatula - a stirring rod

- a beaker - a dropping pippette

EXPERIMENT 1

1. Take a waterproof cloth.

2. With a dropping pipette, put one drop of water onto the waterproof cloth very slowly.

3. Observe what happens.

a) Draw the result in the box on the right. b) Can you still see the drop of water? c) Did the drop of water penetrate the cloth?

EXPERIMENT 2

1. Take the same waterproof cloth.

2. Put some washing powder into water. Stir to dissolve it. 3. With a dropping pipette, put one drop of the water with washing powder very slowly onto the waterproof cloth. 3. Observe what happens.

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PRACTICAL WORK 1: The wetting action of water

OBSERVATIONS:

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FACT FILE 2: Why is water not very good at wetting things?

Surface tension is a property of liquids. Liquids form a kind of tension on their surface. In Practical Work 1 you observed the surface tension of water. Do you remember ?

You can observe the surface tension of water when:

1. You use a dropping pipette and you let a drop of water fall very slowly.

.

2. Before the drop falls, you can see the surface tension of the water. The drop does not have a flat shape, but is rounded.

flat rounded

3. The drop remains rounded because liquids have surface tension. You observed this in experiment 1 from Practical Work 1.

In experiment 1, the liquid you used

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2. How to mix grease with water

Another problem in the process of cleaning is that water alone cannot dissolve grease stains on clothes. In the following experiments you will observe how water and oil react when you mix them together.

PRACTICAL WORK 2: Mixing oil and water

Objective: to compare how oil reacts with water alone and with water and detergent.

Material: You need: - water - oil

- washing powder Lab equipment: You need: - a spatula - a beaker - a stirring rod

EXPERIMENT 1

1. Put oil in a beaker. Add some water. 2. Stir with a stirring rod.

3. Don't touch it for a minute. 4. Observe what happens.

a) Draw what you see in the box on the right. b) Is the oil dissolved in the water?

c) Is the oil mixed with the water?

d) Do the oil and the water form two layers?

EXPERIMENT 2

1. Put oil in a beaker and add some water.

2. Add some detergent and stir with a stirring rod. 3. Don't touch it for one minute.

4. Observe what happens.

a) Draw what you see in the box on the right. b) Is the oil dissolved in the water?

c) Is the oil mixed with the water?

d) Do the oil and the water form two layers?

Draw conclusions: Compare the results of the two experiments. 1. In which experiment is the oil mixed with the water?

(61)

PRACTICAL WORK 2: Mixing oil and water

OBSERVATIONS:

(62)

FACT FILE 3 : Why does oil mix with detergent and water ?

In Experiment 1, Practical Work 2 you observed that oil does not dissolve in water. You saw that:

a) oil and water do not mix

b) oil and water separate into two layers

c) the layer of oil is on top of the layer of water.

When you stir the oil and water, the oil layer breaks down into very small drops of oil. But after a minute or two, these drops of oil join together again and form a layer of oil. So just like at the end of experiment 1, you have two layers: a layer of oil on top of

a layer of water.

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The drops of oil dispersed in water and detergent did not form a layer of oil because the

detergent particles are between the water particles and the oil particles. The detergent particles can be between them because they can mix with water and with oil.

Why can the detergent particles mix with both water and oil particles? Because one side of the detergent particle is "water-loving" or "hydrophilic". This "water-loving" side can mix with the water particle. The other side of the detergent particle is "grease-loving/

(64)

D/ DRAW CONCLUSIONS

Complete the text with the correct word or words.

Grease is one kind of ... on your clothes. Water alone is not good at

eliminating grease. But water with ... can eliminate grease. Detergents can mix with grease and they can ... with water.

You saw that water does not wet very well. Water with ... can wet better than water alone. This is because detergents can break the ... ... of water. Then the water can penetrate the ... much more. So :

1. Detergents can ... with water and grease.

2. Detergents can make water ... better.

Now it's time to answer Marc Rovira's question: What does cleaning mean ?

CLEVER CONSUMERS C/Roger de Llúria, 64 08009 Barcelona

... Dear Marc Rovira,

We are pleased to answer your telephone message dated ...

After doing our laboratory experiments and reading the information our scientists prepared for us, we can summarize the cleaning process for you. Cleaning clothes is a process which ... ... ... ... ...

(65)

1. INTEREST

0 1 2 3

2. PARTICIPATION

0 1 2 3

3. ATTENTION IN CLASS

0 1 2 3

4. PERSONAL EFFORT TO USE ENGLISH IN CLASS 0 1 2 3

6. DIARY 0 1 2 3

(66)

(67)

UNIT 3

ARE ALL THE WATERS THE SAME?

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WHAT DO YOU KNOW ABOUT WATER?

Read the following sentences and decide if they are TRUE or FALSE. If you don't know, circle DON'T KNOW.

1. There is no difference between the water in Madrid and the water in Barcelona.

2. Detergent produces foam more easily in hard water than in soft water.

3. Water hardness is caused by dissolved substances, usually compounds of calcium.

4. Hard water can leave a solid deposit on water pipes.

5. Hard water is located in places where there are salt deposits.

6. Phosphates are chemical substances that can make water soft.

(70)

CONSUMERS WANT TO KNOW

1.

ISIDRO CUESTA’S LETTER

The following letter was sent to the office of the consumer organization "Clever Consumers". Read it carefully and answer the questions on the next page.

C/Mallorca 123,2º 2ª 08015 Barcelona

14 November 1998

CLEVER CONSUMERS C/Roger de Llúria, 64 Barcelona

Dear Sir or Madam,

My neighbour told me about your consumer organization and I am writing to you because I have a question which I hope you can answer.

I am from Madrid, but I have been living in Barcelona for a year. My company transferred me here. I like Barcelona very much and I enjoy living in this beautiful city. I have had only one problem since I have been here.

I live alone and I do all my cooking and cleaning. I have discovered that I need much more detergent to wash the same amount of clothes in Barcelona than I did in Madrid. I use the same biological detergent as I used in Madrid and my clothes are not dirtier so I do not understand why I have to use so much detergent to get my clothes clean. The washing machine in my flat is new and works perfectly. There must be a reason why I need to use so much detergent, but I do not know what it is.

I hope you can answer my question. I look forward to hearing from you and thank you in advance.

(71)

1. Who wrote the letter?

2. Where is the writer of the letter from?

3. Where does the writer of the letter live?

4. How long has the writer of the letter lived there?

5. Who told the writer of the letter about "Clever Consumers"?

6. What problem does the writer have?

7. How long has the writer had this problem?

8. Does the writer know the cause of this problem?

9. Does the writer use the same detergent as before?

(72)

2

. A BRIEF SUMMARY

The secretary of "Clever Consumers" is a very busy person. Complete the blanks to create a brief summary of the letter for the secretary.

... sent us a letter dated ... . Mr.Cuesta is from

... but he has been ... in Barcelona for a ...

He lives alone in a ... in the C/ ... and he does all his cooking and ... Mr. Cuesta's problem is that he uses

... ... in Barcelona than in Madrid. He uses the same ... in Barcelona as he did in Madrid. He ... understand why he needs to use more detergent in ... than in Madrid. His ... ... works perfectly. He wants an

... from "Clever Consumers".

3

. A MEMO FROM “CLEVER CONSUMERS”

You receive this memo from your consumer organization, "Clever Consumers". Read it carefully and underline the question Isidro wants to know.

MEMORANDUMANDUM

DATE: 15 November 1998

SUBJECT:

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LET’S INVESTIGATE

1. This time your RESEARCH TEAM has to answer Isidro Cuesta’s question. Look at the letter again. What does Isidro Cuesta want to know? Copy the question here.

You have to investigate "Why ... ... ...?"

(74)

2.1. In the last Fact File in unit 1 you read about the seven factors which influence the cleaning power of detergents. Do you remember them? Write them here.

1. 2. 3. 4. 5. 6. 7.

2.2. Compare the two situations on the preceding page. What is the same? What is different? Put a cross “X” in the correct column.

THE SAME DIFFERENT the detergent

the amount of detergent the kind of water

the amount of water

the amount of dirt on the clothes washing time

water temperature kinds of movements

2.3. Answer the following questions.

a) What is different in the two situations?

b) Why does Fernando have to use more detergent when he is in Barcelona?

c) Why does Fernando have to use less detergent when he is in Madrid?

(75)

B/ DESIGN THE INVESTIGATION

In this section your RESEARCH TEAM has to plan an investigation to prove that different kinds of water affect the cleaning process of clothes.

1. THINK ABOUT WHAT TO DO

1.1. What do you have to do to prove this?

(76)

2. IDENTIFY THE VARIABLES TO BE CONTROLLED

2.1. Compare these two experiments and discuss the questions below in your teams.

To answer the question “Is it true that you have to use more detergent to wash the same dirty clothes in hard water than in soft water?” you have to compare the cleaning power of the same detergent in two different kinds of water. In experiment 1 the water is soft and in experiment 2 the water is very hard.

EXPERIMENT 1 EXPERIMENT 2

SOFT WATER VERY HARD WATER

a) What is different in the two experiments?

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3. CHOOSE APPROPRIATE LABORATORY EQUIPMENT

What do you need to do your experiments? Look at these pictures and tick only the necessary materials.

LABORATORY EQUIPMENT

beaker Erlenmeyer flat-bottomed funnel flask flask

(conical flask)

(78)

Petri dish test test tube measuring tube rack cylinder

thermometer stopclock mortar stirring or timer rod

(79)

4. DECIDE HOW TO CONTROL THE VARIABLES

Fill in this grid.

CONTROLLED VARIABLES

HOW MUCH? HOW LONG? WHAT TEMPERATURE? LABORATORY EQUIPMENT FOR MEASURING 1. 2. 3. 4. 5.

Congratulations! Now you have defined all the aspects of your investigation. Stop here and compare your data with the other students in class. Your teacher will also help you add other necessary details.

5. DEFINE ALL THE INVESTIGATION IN DETAIL

What will you do in the laboratory? Write all the things to do on the next page. You have to mention every single action. Follow your teacher’s suggestions.

(80)

CLEVER CONSUMERS INVESTIGATION ... Objective:

Material:

Laboratory Equipment:

(81)

C/ DO THE EXPERIMENTS

Now you are in the laboratory. Look at the LABORATORY ROLES and decide who will be the INSTRUCTOR and who will be the RECORDER.

Make sure you have the material and all the laboratory equipment you need.

Fill in the observation grid you have on the next page while doing the experiment.

HELP

OBSERVATIONS: What things can you observe while doing the two experiments?

1. How much foam is there in each beaker?

2. In which kind of water does the detergent make more foam (bubbles)?

3. How long does the foam last in each test tube?

4. How clear is the water in each test tube after shaking it for the first time? (clear, cloudy, with particles)

5. In which test tube does the detergent dissolve better?

6. ...?

How are you going to take note of all this? Design a grid to take note of all these details.

PROBLEMS:

(82)

INVESTIGATION ... : ... Instructor:... Performer 1: ... Performer 2: ...

(83)

D/ OBSERVE AND RECORD THE RESULTS

1. Complete this grid with the results of your experiments.

distilled water 4g CaCl2 + distilled water

tap water from ... Height of the foam

after shaking 1 drop of distilled water and detergent Appearance of the water after shaking the test tube for the first time

Number of drops of distilled water and detergent to make 1 cm of foam

2. Compare your results with the data from the other research teams. Calculate the average and write your final results here.

distilled water 4g CaCl2 + distilled water

tap water from ... Height of the foam

after putting 1 drop of distilled water and detergent Appearance of the water after shaking the test tube for the first time

(84)

E/ DRAW CONCLUSIONS

1. Answer the following questions.

1. Which test tube contained the hardest water?

2. Why?

3. Which test tube contained the softest water?

4. Why?

5. According to the results of your experiments, is the tap water in your school soft, hard or very hard?

6. Why?

7. In which kind of water did the detergent make more foam (bubbles)?

8. In which kind of water did the foam last longer?

9. In which kind of water did the detergent dissolve better?

10. Why?

2. Complete this conclusion.

You need ... detergent to produce foam with ... water.

3. Now you can answer the question:

(85)

2.

Use this information to answer Isidro Cuesta’s question.

Now you can explain to Isidro Cuesta why he uses more detergent in Barcelona than in Madrid. Complete the following letter with the results of your investigation.

CLEVER CONSUMERS

C/ Roger de Llúria, 64 08009 Barcelona

... ...

Dear ...,

We are pleased to answer your letter dated ... concerning ...

After our laboratory experiments, our scientists say that ...

...

(86)

FACT FILE 1: What is hard water?

When water runs over rocks and soil, insoluble substances enter the water and make it hard. For example, if the rocks have compounds of calcium (Ca), the rocks are calcareous. When the water runs through calcareous rocks, these compounds of calcium (Ca) enter the water and the water becomes calcareous. Look at the colour of the water in the following photograph.

Noguera Ribagorçana, Congost de Bonrebei, el Montsec.

The composition of the soil and rocks of the place the water runs through determines if the water is soft, hard or very hard. A geological map can indicate the characteristics of the water in a certain place. The three colours on the following map show you different areas in Spain according to the type of water.

(87)

Hard water is the water which contains other substances. These other substances may be compounds of calcium (Ca), magnesium (Mg), ... These substances do not dissolve in water. You can see white solid deposits of these substances on the sinks, taps, places where the water has been. These deposits can also damage washing machines.

Hard water deposits on the coil of a washing machine

How does water hardness affect the process of cleaning clothes?

Detergent does not dissolve easily in very hard water because very hard water contains some substances which are insoluble. These substances, calcium (Ca) and magnesium (Mg), do not dissolve in water. They make it difficult for the detergent to dissolve in water. If the detergent cannot dissolve completely, you have to use a bigger amount of detergent to maintain the cleaning power of the detergent.

Consequently, the harder the water, the more detergent you need to clean clothes.

Water softeners: a solution to the problem of hard water

(88)

1. Answer the following questions about the text. 1. What is water hardness? Define it.

2. What problems does water hardness cause?

a)

b)

3. If your tap water is very hard, why do you need more detergent for the same amount of water?

4. What is a water softener? Define it.

5. What is the name of one chemical product that is used to soften water?

6. Are phosphates safe for the environment?

7. What kind of detergents are better for the environment?

8. Can a detergent with phosphates be considered a biological detergent?

9. Why (not)?

(89)

2. Fill in the blanks with the correct information.

Phosphates are one of the ... (1) of detergents. They ... (2) water, that is, they make water less hard. Phosphates help to eliminate some insoluble substances, like ... (3) or ... (4). This means that phosphates increase the cleaning power of ... (5).

FIELD WORK 1: Detergent labels

1. Look at the map of Spain in the “Fact File 1: What is hard water?”. Is the water in the place where you live soft, hard or very hard?

2. Read the instructions on the box of the detergent you use to wash clothes at home. What is the amount of detergent recommended for soft water, hard water and very hard water? Write the recommended amount in the empty boxes.

3. So what amount of detergent should you use?

4. Compare the recommended amounts of your detergent with those of the other students. Do the amounts vary according to the type of water?

(90)

SELF-ASSESSMENT ON SCIENCE SKILLS

Give yourself a mark on each step of your investigation.

DESIGNING YOUR EXPERIMENTS

1. We chose appropriate laboratory equipment. 0 1 2 2. We chose an appropiate amount of detergent. 0 1 2 3. We chose an appropriate amount of water. 0 1 2 4. I wrote all the steps of the experiments in detail 0 1 2 3 4

PERFORMING YOUR EXPERIMENTS

1. To measure the amount of water, I used : a) a beaker

b) a measuring cylinder

c) a measuring cylinder and a dropping pipette

0 1 2 2. To measure the amount of detergent, I used:

a) the electronic balance

b) the electronic balance and a ... ...

0 1 2 3. To measure the water temperature, I put a

thermometer into the water for 5 minutes. 0 1 2 4. I followed all the steps in the correct order

and at the same time. 0 1 2 5. I worked with the other members of my group

and helped them. 0 1 2 6. I observed carefully and took notes during the

experiments 0 1 2

1. Do you think that the results of your experiments are reliable? 100% reliable

50% reliable 25% reliable 0% reliable

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SELF-ASSESSMENT ON LANGUAGE SKILLS

USE OF ENGLISH

LISTENING

COMPREHENSION

1. I could understand the teachers' oral

instructions and explanations. 0 1 2

READING

COMPREHENSION

2. I could understand all the written instructions

to the exercises. 0 1 2

VOCABULARY 3. I tried to use English to name the laboratory

equipment. 0 1 2

WRITING 4. I could write the diary comments and the

instructions of the experiments in English. 0 1 2

SPEAKING 5. I tried to use English to give all the oral

instructions of the experiment when I was the

instructor. 0 1 2

SPEAKING

.

6. I tried to use English to ask questions to the teachers, ask for things to my classmates and

discuss problems in my group. 0 1 2

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1. INTEREST 0 1 2 3

2. PARTICIPATION 0 1 2 3

3. ATTENTION IN CLASS 0 1 2 3

4. PERSONAL EFFORT TO USE

ENGLISH IN CLASS 0 1 2 3

6. DIARY 0 1 2 3

7. HOMEWORK 0 1 2 3

(93)

CLEAN CLOTHES, DIRTY RIVERS?

CONSUMERS WANT TO KNOW : - listen to an interview with the Mayoress of Sant Vicenç del Munt on a radio programme

(94)

(95)

WHAT DO YOU KNOW ABOUT DETERGENTS ?

Read the following sentences and decide if they are TRUE or FALSE. If you don't know, circle DON'T KNOW.

1. All the detergents produced in Spain are

biodegradable. TRUE FALSE DON'T_KNOW

2. Detergents are chemical products. _TRUE _FALSE DON'T KNOW

3. All the ingredients in a detergent are necessary

to clean clothes.

4. Spanish legislation says that all the

ingredients in a detergent must be listed on the box.

5. Phosphates are nutrients for the algae that live

in lakes and rivers. TRUE FALSE DON'T_KNOW

6. We consume about 10 kg of detergent

per person per year. TRUE FALSE

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CONSUMERS WANT TO YOU KNOW

Cliqueu sobre aquesta icona

1

. AN INTERVIEW WITH MARIA PUIG, THE MAYORESS OF SANT VICENÇ DEL MUNT.

The secretary of “Clever Consumers” taped this radio interview. Listen to the interview carefully and complete the following sentences.

1. VSV is the local radio station in ...

2. Maria Puig is the ... of Sant Vicenç del Munt.

3. They want to build a big industrial ... near Sant Vicenç del Munt.

4. The town hall ... made a decision. They are studying the situation.

5. The waste from the laundry will go into the ...

6. This waste water will contain ... and other chemical substances.

7. These chemical substances come from the ... that are used in industrial laundries.

8. The waste water could ... the water in the lake and be ... for aquatic life.

9. The mayoress and the town hall nees the help and advice of scientist and ...

(97)

2

. A MEMO FROM “CLEVER CONSUMERS”

You receive this memo from your consumer organization, "Clever Consumers". Read it carefully, and underline the information you have to look for.

MEMORANDUM

DATE: 30 November 1998

(98)

LET’S FIND OUT

1.

This time your RESEARCH TEAM has to help the mayoress of Sant Vicenç del Munt. What does the mayoress want to know? Copy the question here.

You have to find out "... ...?"

B/ LOOK FOR INFORMATION

1.

The detergents we use to wash our clothes have many ingredients. All of these ingredients are chemical substances and each ingredient has a specific function in the process of cleaning.

Here are some of the common ingredients of detergents. Do any of them sound familiar to you? Circle the ingredients which sound familiar to you.

1. "activadors del color" 2. "tensioactius"

3. "fosfats" 4. "enzimes"

5. "blanquejadors" 6. "efecte llexiu" 7. "anti-calcaris" 8. “oxigen actiu”

2.

On the following page there is some information from our laboratory chemists and experts. Use the information from Fact File 1 to complete this table.

CATALAN ENGLISH FUNCTION

activadors del color tensioactius

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FACT FILE 1: The most commom ingredients in detergents

1. synthetic detergent or soap: they are surface-active agents. They have three functions (see Fact File 1: What does cleaning mean? in unit 2):

1. they reduce the surface tension of water and make the water penetrate the fibres of the cloth more easily

2. they mix grease/dirt with water. This means they help to separate grease/dirt

from the fibres of the cloth

3. they suspend the dirt in the water so that it can be washed away.

Depending on the proportion, they give more or less foam to the detergent.

Surface-active agents can be: 1. anionic 2. non-anionic 3. soaps

2. builders: they are complex chemicals. They soften the water (i.e. make the water less hard). They help the surface-active agents to penetrate the fabrics better and clean better, especially they eliminate clay particles.

They can be: 1. phosphates 2. zeolites 3. carbonates

(100)

6. brightening agents: make "whites" and coloureds brighter at lower

temperatures. EDTA is one of these substances. Its use is not recommended, because it is difficult to degrade.

7. metal protector: protects aluminium parts of washing machines.

8. perfume: gives clothes a fresh, clean fragance.

FACT FILE 2: Characteristics of biological detergents

CONCENTRATED

WASHING POWDER

New Natural Fruit Fragance

Phosphate-free No NTA No EDTA No enzymes

No optical brighteners

Not tested on animals

Contains no animals products

Recycled cardboards

This is the label of an ideal biological detergent. This detergent cleans our clothes, but does not pollute our water. Are there any completely enviromentally-safe detergents on the market? Unfortunately, no, there aren't any at present. But when you go shopping, read the labels on the box or bottle of detergent to see how safe or how bad it is for the environment.

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b) detergents with non-ionic surface active agents decompose into chemical wastes which are more toxic and non-biodegradable. It is better to use a detergent with anionic surface active agents.

2. Substitutes for Phosphates:

Phosphates are an important cause of water pollution and are prohibited in many countries. However, some of their substitutes are also bad for the environment. You should buy detergents without phosphates and without NTA, a phosphate substitute which can be toxic for aquatic life.

3. Whiteners:

Whiteners are another common ingredient in detergents. EDTA is a chemical used to whiten clothes, but EDTA is not easily biodegradable. The French government has limited the use of EDTA in detergents.

4. Enzymes:

Enzymes help eliminate protein stains (e.g. blood, egg, etc.), but they can also enter our clothes and consequently irritate our skin. In Germany, doctors recommend that parents wash their children's clothes with enzyme-free detergents.

FACT FILE 2 EXERCISES

1.

Read Fact File 2. What are the characteristics of a biological detergent?

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-FIELD WORK 1: A comparative analysis of concentrated washing powders

1.

Each member of your research team has to go to the supermarket and complete the information in this grid about concentrated washing powders.

Brand Colon ultra Skip poder Flota Ultra Luzil micro plus Dixan mega perls Dash acción lejía Casa Verde Ariel Ultra Punto matic Net weight Washings per box Anionic Non-Anionic Soap Phosphates Zeolites Carbonates Enzymes Whiteners Perborates EDTA

Cost in ptas

(103)

2.

This table shows a comparative analysis of concentrated washing powders. It is adapted from the magazine of a Spanish consumer organization called

“Ciudadanos” (November, 1994).

Brand Colon ultra Skip poder Flota Ultra Luzil micro plus Dixan mega-perls Dash acción lejia Casa Verde Ariel Ultra Punto matic

Net weight 2 kg 1.7 kg 2 kg 2 kg 1.6 kg 2 kg 2 kg 2 kg 1.52 kg Washings

per box 20 18 26 19 22 22 17 22 16

Anionic 5.9 8.4 5.9 8.6 13.4 7.4 0 7.8 17.6

Non-Anionic 9 13.9 3.6 8.7 5.9 6.1 5.6 7.2 3.6

Soap 0.5 0.8 1.2 0.6 1.4 0.6 1.5 0.6 0.4

Phosphates 32.7 0 23.9 0 0 0 0 0 0

Zeolites 0 34.1 0 33.3 19.1 17.8 32.9 14 0

Carbonates 13.9 16.7 7.9 22.6 6.2 16.9 28.6 16.9 0

Enzymes Yes Yes Yes Yes Yes Yes Yes Yes Yes

(104)

Look at the table on the former page and answer the following questions.

1. Which washing powder contains more EDTA ?

2. Which washing powder contains more phosphates ?

3. Which chemical products are used to "whiten" clothes ?

4. Which washing powder is the cheapest ?

5. Which washing powder is the most expensive ?

6. If the washing powder does not contain phosphates, what products does it use to soften the water ?

7. Is there any washing powder that cannot remove protein stains ? (egg stains, blood stains, etc.)

8. Which washing powder contains the largest amount of harmful substances ?

List the harmful substances:

9. Which washing powder do you think is the least harmful ?

Why ?

(105)

FACT FILE 3: Where do the detergents you use at home go?

When our washing machine has completed its cycle, the water is drained from the machine into our local sewage system.

(106)

What is the impact of phosphates on the environment ?

Phosphates are nutrients for the algae, bacteria and other microorganisms that live in bodies of water (streams, rivers, lakes). When there is a high concentration of phosphates in the water of rivers and lakes, there is an increase in the amount of microorganisms. Why? Because these microorganisms have more food than usual. As a result, algae, bacteria and other microorganisms multiply rapidly.

When the algae, bacteria and microorganisms die, they descend to the bottom of the lake. There they are decomposed by decomposing organisms: fungi, aerobic and anaerobic bacteria. Decomposing organisms eliminate organic matter (the dead microorganisms) but when they do this, they consume a lot of oxygen.

(107)

(108)

FACT FILES 3 EXERCISES

1.

Are the following sentences TRUE or FALSE? Circle the correct answer.

1. Phosphates in detergents are destroyed before they get into bodies of water (lakes, streams, rives).

TRUE / FALSE

2. Algae, bacteria and other microorganisms which live in lakes and rivers eat the phosphates which enter these bodies of water with waste water.

TRUE / FALSE

3. Fish are microorganisms. TRUE / FALSE

4. Manufacturers put phosphates in detergents to make water hard.

TRUE / FALSE

5. When there is a very large amount of phosphates in a lake or river, the fish die of asphyxiation.

TRUE / FALSE

6. Organic matter can only be decomposed by decomposing organisms.

TRUE / FALSE

7. Decomposing organisms need a lot of oxygen (O2) to decompose organic matter.

TRUE / FALSE

8. Algae, bacteria and other microorganisms absorb most of the oxygen (O2) in the water.

TRUE / FALSE

9. When decomposing organisms decompose a large amount of organic matter, they can consume most of the oxygen (O2) from

(109)

C/ DRAW CONCLUSIONS

1.

PROS AND CONS

The mayoress and the people of Sant Vicenç del Munt have to make a decision: should they allow "Clean Clothes Inc." to build an industrial laundry near their lake? What are the "pros" and "cons" of this question? Will the laundry be beneficial for the people of Sant Vicenç? It is not easy to decide. The mayoress has written some points, pro and con. Write some ideas about the positive and negative aspects of the construction of the industrial laundry.

PRO CON

1. The people of Sant Vicenç can get jobs at the laundry.