Inquiring with science - gsctatehood - home2+Science.pdf · Inquiring with science What makes good scientific ... Do TV ads tell the whole truth? ... you which is the best dishwashing

2Inquiring with science

What makes good scientific inquiry? Plastic wrap – also known as cling wrap or cling film – was discovered in 1953 after a scientific experiment did not go quite as planned. An American scientist was trying to make a hard plastic cover for his car. The plastic that he made did not quite turn out as he expected. Instead of being hard, it was a thin, flexible film. Rather than throw out this failure, the scientist worked with the thin plastic, trying it out for different uses. And that is how plastic wrap was invented.

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What do you already know about scientific inquiry?You probably encounter plastic wrap every day. It might be around your lunch in your school bag, or around the sandwich that you buy at the school canteen. It could be covering yesterday’s leftovers in the fridge at home. There are many annoying things about plastic wrap. Sometimes

Figure 2.1 Plastic wrap needs to be strong.

WORKSPACEWhich brand of plastic wrap is the strongest?SCI07SIWR07208

Work in a group of two or three students. Work out a method you could use to find out which brand of plastic wrap is the strongest.

You need• three different brands of plastic wrap• other equipment as requested

What to do

1 Observe and feel each brand of plastic wrap. Predict which brand you think will be the strongest. Record your prediction.

2 Work out how you are going to test the strength of each plastic wrap. Ask your teacher for any equipment that you may need.

3 Write down your method of testing and list all the equipment that you use.

4 Perform your method.

What did you discover?

1 Write down your results.

2 From your results, which brand of plastic wrap did you find to be the strongest?

3 Do your results match your prediction?

What do you think?

4 Discuss with the rest of the class the method that your group used. How did other groups differ in their method to test their plastic wrap?

5 List anything else, other than the strength of the wrap, that could have affected your results.

Which brand of plastic wrap is the strongest?Activity 2.1

it doesn’t tear straight, sometimes it sticks to itself and sometimes it doesn’t stick properly. But the most annoying thing of all would be if the plastic wrap was not strong enough. Imagine if the plastic wrap around your sandwich broke, and the filling from your egg sandwich ended up all over the contents of your schoolbag. Plastic wrap needs to be strong.

In the following activity you will have the opportunity to show what you already know about scientific inquiry.

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glossary termmethodthe set of steps that you take to conduct a scientific investigation

Do TV ads tell the whole truth?Culminating assessment task

Television advertisements specialise in telling you which is the best dishwashing detergent, paper towel or insect killer. How reliable are advertisers’ claims, and are they backed up by scientific testing?

Your task

Select a common household product. Design a fair test to find out if that product is the best at what it does. For example:

• Which sticky tape is the stickiest?

• Which laundry detergent cleans clothes the best?

• Which elastic band is the most stretchy?

• Which dishwashing liquid cleans dishes the best?

What to do

1 Decide on the question you want answered.

2 Predict what the answer might be.

3 Work out a method to test your prediction. Make sure that it will test what you want it to test.

4 List your variables. Identify your independent and dependent variables. What variables will you need to control?

5 Plan what equipment you need.

6 Consider any safety risks and take action to reduce them.

7 What sorts of results will you collect? How will you collect them?

8 How will you display your results?

9 Perform your method.


1 Did your results agree with your prediction?

What do you think?

2 How could your method have been improved?

Presentation

3 Write up your experiment using the report-writing format on page 39.

Take digital photos to illustrate your method and results, and include these in your report. Upload your final report to the class wiki.

WEB 2.0

ACTIVITY SHEETRubric: Do TV ads tell the whole truth?SCI07SIAS07200

Figure 2.2 Which washes whitest?

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Types of dataWhen you undertake a scientific experiment, there are several different types of data that you might collect. The type of data will depend on the experiment you are doing, how you are doing it, what you want to find out and how you collect the data.

Which is the nicest biscuit?Activity 2.2

WORKSPACEWhich is the nicest biscuit?SCI07SIWR07226

Figure 2.3 Which do you like best?

You need• three different types of biscuits • a blindfold

What to do

1 Work with a partner. One person is the experimenter and the other person is the taster.

2 The taster is blindfolded.

3 The experimenter hands a biscuit to the taster and asks him or her to taste it.

4 Repeat step 3 for the other biscuits.

5 The taster says which of the biscuits he or she likes best. Write down, or record, their choice.


1 Share your results with the class. Did all the tasters agree on which was the nicest biscuit? Give two reasons to explain the class results.

2 Using the class results, how would you answer the question posed by this activity?

What do you think?

3 Do you think this was a fair test? What could you suggest to make it fairer?

Extension

Complete a DIGA tool as a way to reflect on the process used to determine which biscuit was the nicest. DIGA stands for Describe, Interpret, Generalise and Apply.

4 State the aim of the DIGA.

5 Describe what happened in this activity.

6 Interpret what happened by asking: a Why did we do this activity? b What did it mean to each person? c Did it make sense to you? d Think of three other questions you could

ask and answer them.

7 Generalise the experience.

8 Apply what you have learnt in this activity to other situations by asking questions such as:

a How does what I have learnt from this activity apply to . . .?

b How can I use what I have learnt here in other subjects?

What are the risks in doing this activity? How can you manage these risks to stay safe?

Some students may have allergic reactions to some biscuits.

Science laboratory benches and glassware may have chemical contamination.

If you have any food allergies, let the teacher know before you start.

Perform this activity in a regular classroom, not a science lab.

Qualitative data Qualitative data includes almost any information that is not numerical. Examples include gender, country of birth, hair colour, favourite things and options such as yes–no responses. Qualitative data can include what people think and feel, which may be different for each person. In Activity 2.1 on page 22, qualitative data included how the plastic wrap felt when you touched it. You cannot put a numerical figure on how something felt.

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Quantitative dataQuantitative data is information that can be counted or measured and expressed as numbers. The number of eggs in a bird’s nest, the number of whales observed on a certain day and the number of weights you can hang on a rubber band before it breaks are all examples of data that is counted. Information about temperature, length, mass,

Figure 2.4 Measuring instruments are used to gather quantitative data.

capacity and so on can be measured in degrees, metres, kilograms and litres. Some measuring instruments used to collect quantitative data are shown in Figure 2.4.

Quantitative data can be ranked: you can compare two items of the same kind and say which is greater. It can be displayed in tables and represented visually in graphs.

glossary termsdatainformation that is gathered from surveys and experiments and used for making calculations or drawing conclusionsqualitative datanon-numerical data that relates to a quality, type, choice or opinion

quantitative datanumerical information that is counted or measured and expressed as numbersrecordto write down

Points of differenceActivity 2.3

WORKSPACEPoints of differenceSCI07SIWR07209

Which part of the body is the most sensitive to touch?

You need• 2 washable markers of different colours• a blindfold• a ruler

What to do

1 Work with a partner. Decide who will be person A and who will be person B. Blindfold person B.

2 Person A uses one of the coloured markers to make a dot on the back of person B’s hand.

3 Person B uses the other coloured marker to make a dot on their own hand, in the spot they think was marked by person A.

4 Repeat this process on the forearm, upper arm, lower leg, back of knee and front of knee.

5 Use the ruler to measure the distances (in millimetres) between each pair of dots.

6 Record your quantitative data – the distance between pairs of dots – in the table in the workspace.


1 On which part of the body was the distance between the two dots the greatest?

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The difference between qualitative and quantitative dataQualitative data describes a quality, whereas quantitative data measures a quantity. Table 2.1 outlines the differences between them. Read through the examples in the table. Complete the activity sheet ‘Differences between data’ to record examples of your own.

Table 2.1 The difference between qualitative and quantitative data

Qualitative data Quantitative data

Think: qualitative 5 quality

This data describes what is seen and observed. It does not measure anything. It looks at things like colours, textures, smells, tastes, appearances and perceptions.

Think: quantitative 5 quantity

This data deals with numbers and things that can be counted or measured and represented graphically or in charts and tables.

Example 1: A café

The walls are textured, like stone.

The cabinets have glass doors and stainless-steel counters.

There are wooden tables, and chairs with leather seats.

There are floral curtains on the windows.

Example 1: A café

The café measures 10 m 3 15 m.

There are 4 separate glass cabinets, each measuring 2 m 3 1 m 3 1 m.

There are 12 circular tables with a diameter of 75 cm.

The front window measures 150 cm 3 180 cm.

Example 2: A Year 7 Science class

The students are friendly.

There is a mixture of boys and girls.

The students are noisy and playful.

Example 2: A Year 7 Science class

There are 26 students in the class.

There are 14 girls and 12 boys.

The students are aged 12, 13 or 14.

Example 3: A birthday party

There a lots of boys and girls.

There is a chocolate birthday cake.

There are party pies, sausage rolls and cupcakes.

There are balloons, loud music and streamers.

There is cordial or water to drink.

Example 3: A birthday party

There are 8 boys and 6 girls.

There is one birthday cake, with 8 candles.

There are 2 dozen sausage rolls, 3 dozen party pies and 24 cupcakes.

There are 40 balloons.

There are 6 L of red cordial, 2 L of green cordial and 6 L of water.

ACTIVITY SHEETDifferences between dataSCI07SIAS07201

2 On which part of the body was the distance between the two dots the least?

3 Which part of the body did your group find to be the most sensitive to touch?

4 Share your results with the rest of the class.

What do you think?

5 Using the class results, now answer the question posed at the beginning of this activity.

6 Do you think this test was a fair test? Explain your answer.

Share your results by uploading them to the class wiki.

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What makes a good scientist?

WORKSPACEScientist wantedSCI07SHWR07211

1 Imagine that you are an employer. You need a scientist to work for you. Write an advertisement that describes the job vacancy and clearly states the skills and abilities that you are looking for. Hint: It would be a good idea to consider the Habits of Mind (see Unit 1). You could list the habits that you would value in an employee, such as persistence.

2 Look at the advertisements that other students have written.

3 Select one of these. Pretend that you are a scientist and write an application for the job that you chose.

Once you have written your job advertisement, upload it to the class wiki.

WEB 2.0

Scientist wantedActivity 2.4

What have you learnt?Questions 2.1

Understand

1 Explain the difference between qualitative and quantitative data.

Apply

2 Identify which of the following sets of data are qualitative and which are quantitative.a 106 more people like chocolate milk than

strawberry milk.b Sheryl prefers to buy red shirts rather than

green shirts.

c Louise caught the bus to school 26 times and walked 11 times.

d Naman likes the smell of chocolate more than the smell of bananas.

e Daniel likes using black pens instead of blue pens.

3 What is the purpose of gathering data?

4 Do all scientists gather the same sort of data? Discuss, using examples.

Synthesise

5 Give three examples of qualitative data and three examples of quantitative data.

Reflect

6 In your opinion, which is more reliable: qualitative or quantitative data? Explain your reasoning.

WORKSPACEWhat have you learnt? 2.1SCI07SUWR07210

A scientist is honest and ethicalIt is important that scientists are always honest in their reporting. For example, they must not leave out some of their data if it doesn’t show what they were hoping to find. They must explain the methods they used so that other scientists can understand their results, and try the experiment themselves.

Scientists need to be very careful about acknowledging the contributions and help of other people. Whenever scientists make use of any other person’s work, reports or findings, they must acknowledge the sources they used.

A scientist can work in a team Not many scientists work alone; many work in teams. To work well as a team, scientists need a range of skills. Most of your class work in Science will involve working collaboratively in groups or teams. You might like to complete the activity sheet ‘ Working in a team’ to help you identify what makes a good team. You could carry out the experiment about temperature changes to see how well you work in a team.

ACTIVITY SHEET Working in a teamSCI07SIAS07202

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Figure 2.6 Scientists need to work in teams.

Hints for teamwork

• Members of the team need to listen respectfully to everyone’s ideas and opinions. Use the Habit of Mind ‘listening with empathy and understanding’. This means that you make a conscious effort to understand other people’s thoughts, ideas, points of view and emotions.

• If your team cannot agree on some point, be prepared to compromise.

• Your team’s work should be planned so that each member of the team has a fair share of responsibility. Refer to the Habits of Mind to identify the strengths of individual team members, and allocate tasks accordingly. It is often a good idea to have a team leader who oversees the team’s progress, and someone who reports back to the teacher or class.

• Your team could draw up a chart to record what was done, and by whom. You could also include a plan on how to progress if someone in the team is unable to complete a task.

Use Google Docs to draw up a chart for everyone to contribute to. This will be a good way to monitor progress.

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ACTIVITY SHEET Team experiment – temperature changesSCI07SIAS07203

wow! In 1879, Russian-born chemist Constantin Fahlberg was experimenting with different uses for coal tar in the laboratory at Johns Hopkins University, Maryland, USA. One evening he left the lab to go home, but failed to wash his hands. While eating a bread roll for dinner, he noticed that it tasted sweet. Fahlberg and the head of the laboratory, Ira Remsen, published several articles about this sweet substance. Later, Fahlberg named it saccharin, and he grew wealthy when it became widely used as a sweetener. However, Remsen was angry that he didn’t get any credit for a discovery that had been made in his laboratory.

How sweet it is!

Figure 2.5 Should Fahlberg have acknowledged Remsen in his discovery of saccharin?

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Table 2.2 Safety hints and hazards in the science laboratory

Act safely when you or others are using glassware.

Always treat hot things with care. Running in the science laboratory can cause accidents.

Not wearing safety gear when needed can result in injuries.

Loose clothing or long hair can get caught on things or catch fire.

Always have an organised workplace.

Safety messagesActivity 2.5

WORKSPACESafety messagesSCI07SIWR07212

Choose one of the pictures in Table 2.2. Develop a safety message about that situation and present it to the class. (Use the workspace to plan your message.) You must use information and communications technology (ICT) to communicate your message. For example, you might like to develop a short movie, a podcast, an advertisement, a brochure, a poster or a slide show.

Scientists are safety conscious No matter where a scientist or science student works, the first consideration must always be safety. To be safe in your workplace, you need to be alert at all times. Many accidents occur as a result of careless behaviour. Table 2.2 on pages 29–30 shows some of the hazards when working in a science laboratory.

Figure 2.7 Scientists must wear suitable safety gear.

As a class, develop your own set of safety rules. Upload these to the class wiki. Over the course of the year, add to the rules to assist with class and personal safety.

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Table 2.2 Safety hints and hazards in the science laboratory (continued)

Items left close to the edge of a bench can easily fall off.

Never touch, smell, taste or mix substances unless told to by your teacher.

Always be careful when using a Bunsen burner.

Do not leave a lit Bunsen burner unattended.

Be careful with boiling liquids. Do not eat or drink in the science laboratory.

Hazchem

Hazchem is a hazard warning system used in Australia, New Zealand, Malaysia and the United Kingdom. Hazchem warnings are used on vehicles transporting hazardous substances and in places where those substances are stored. Symbols are used to indicate what danger the

Figure 2.8 Hazchem symbols

substance presents. A sign or special plate also provides information that tells emergency services, such as the fire brigade, what precautions they need to take when dealing with the substance. Figure 2.8 shows some of the Hazchem symbols you may have seen.

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ACTIVITY SHEETHazchem symbolsSCI07SIAS07204

Safe use of science equipment

During Science classes, you will use many different types of equipment. To get the best results from your experiments, it is important that you learn how to use this equipment correctly. Some of the equipment is expensive, dangerous or breakable. The videos show just a few of the skills that you will need to learn during your science classes.

VIDEO How to pour a liquidSCI07SUVD07221

VIDEO How to measure a liquidSCI07SUVD07222

VIDEO How to set up and light a Bunsen burnerSCI07SUVD07223

VIDEO How to use a Bunsen burner to heat a test tubeSCI07SUVD07224

Hazchem in the science labActivity 2.6

WORKSPACEHazchem in the science labSCI07SUWR07213

1 Are there any Hazchem signs or symbols in and around the Science labs at your school? If so, what are they and where are they located?

2 Do you think the signs are in the best places? If not, explain where you think they should be placed, and why.

Storyboarding safetyActivity 2.7

Working in a group of two or three, choose one of the following topics. Create a storyboard and movie for your topic showing how to use the equipment safely.• How to safely light a Bunsen burner • How to use a data logger with a

temperature probe• How to measure a liquid in a measuring cylinder

Use Inspiration, VISIO or freeware from the web to create your storyboard. Upload your storyboard and movie to the class wiki.

WEB 2.0

glossary termHazchema system that warns people of potential hazards related to transported or stored substances


Understand

1 What are some of the personal qualities that make a good scientist?

2 List five reasons why you need to be aware of safety when working in the science room or laboratory.

3 What is the Hazchem system? List two reasons for using this system in Australia.

Apply

4 What action would you take:a if a chemical is spilt in the science labb if you smell leaking gasc if you see students running in the labd if you are feeling dizzy or having difficulty

breathing?


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The scientific methodScientists have devised a consistent approach to conducting scientific investigation. We now call this the scientific method. The scientific method is a set of steps that enables scientists to plan and conduct experiments in a consistent and repeatable way.

The basic steps of the scientific method are as follows.• Ask a question.• Formulate a hypothesis.• Plan and carry out your investigation.• Collect and analyse your data.• Draw conclusions and evaluate your investigation.

Ask a questionUsing observation of the world around you, formulate a question. The question could begin with: what, why, how, which, who or where. Examples are:• Why do kookaburras laugh?• How do cats learn where their food bowl is?• Which glue is the best for sticking wood to cardboard?• Why can’t my pen write on greasy paper?

Formulate a hypothesisA hypothesis is an educated guess or prediction that can be tested in a scientific way. The hypothesis is often in the form of: ‘If . . . then . . .’ For example:

Question: Will water boil more quickly if salt is added to it?

Hypothesis: If I add salt to water, then the water will boil more quickly.

In scientific terminology, it is not possible to prove a hypothesis. The results of an investigation either support or refute your hypothesis.

Figure 2.9 Does adding salt to water make it boil more quickly?

Plan and carry out your investigationAny scientific investigation must be a fair test. To create a fair test, you need to understand variables. A variable is a factor that can change. In an investigation or experiment, usually several variables may affect the results. Therefore, it is important to carefully plan a fair test in which only one variable is changed and the others are kept the same or controlled. You must set up your investigation so that you are testing what you think you are testing, and that it is clear that nothing else is influencing the results.

When testing the water and salt hypothesis, you need to measure the boiling point of water with different amounts of salt. The variables that could affect your results include the size of the container, the amount of water, the starting temperature of the water, the heating apparatus used and how you determine if the water is boiling. You would need to control or keep all these variables exactly the same.

The different types of variables are as follows.• The independent variable is what you choose to change

in your experiment. In our example, the independent variable is the salt added to the water.

• The dependent variable is what you choose to observe. It changes as a result of a change to the independent variable. In this case, the dependent variable is the time it takes for the water to boil.

• Controlled variables are variables that need to stay the same throughout the experiment. In this example, these are the size of the container, the amount of water, how the containers are heated and how you determine if the water is boiling.

5 Think of two other safety issues. State how you would deal with each.

6 List five places (apart from the science classroom) where you have seen Hazchem signs.

Reflect

7 Do you think Hazchem should be an international system? Why, or why not?

Share a question and related hypothesis on the class wiki.

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glossary termscontrol a scientific set-up that does not include the independent variable to be tested; used to provide baseline data controlled variable a factor that needs to be kept the same throughout a scientific investigation so that it does not influence the resultsdependent variable the factor that changes as a result of the independent variable; the factor that can be measured or countedfair test a scientific investigation in which there is an independent variable and one or more dependent variables; all other variables are controlled

hypothesis an educated guess or prediction that can be tested in a scientific way, usually written in the form: ‘If . . . then . . .’ independent variable the factor that you choose to vary in your investigationrefuteto show to be false; to disprovescientific method a set of rules that enables scientists to plan and conduct experiments in a consistent and repeatable wayvariablea factor that could influence the result of an investigation

In our water–salt example, water without any salt at all is called a control. This gives a base line against which the other data can be compared.

Figure 2.10 An experimental set-up showing time is the dependent variable and salt is the independent variable.

One way to make sure that your result is accurate is to repeat the experiment several times. If you always get the same result, you can be fairly sure this was not due to luck or accident. Repeatability is an important part of the scientific method. If a scientific finding is to be taken seriously, other scientists must be able to follow the same method and achieve the same results.

So, for an experiment to be valid it must:• clearly test the hypothesis• be a fair test• be repeatable.

Collect and analyse your dataBefore you start an experiment you need to think about the data you will collect. In the salt–water example, you will be timing how long it takes for the water to boil. But will this be measured in seconds or minutes? How will you decide when the water is boiling? (Will you simply watch out for bubbles?) Will you repeat the experiment with different amounts of salt? How will you record this data? Will you write it down, video it or both?

When you have collected all your data, what are you going to do with it? How are you going to analyse it or work out what it is telling you? How are you going to work out if your data is accurate?

Draw conclusions and evaluate your investigationOnce you have worked out what your data is telling you, you need to look back at your hypothesis. Does the data support or refute the hypothesis?

You also need to look back at your experimental method. Did you encounter any problems, limitations or faults that would need fixing if you were to carry out this investigation again?

INTERACTIVE Fair test – growing lettuceSCI07SUIN07225

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Fair testing – which paper towel? Investigation 2.1

Your challenge

Working in a group of two or three, plan and carry out a fair test to find out which paper towel is the most absorbent. Make sure that you test at least three different types of paper towels.

This might help

Reread the section on the scientific method (pages 32–33). Consider:

• What is your question?

• What is your hypothesis?

• What equipment are you going to need?

• What safety issues do you need to consider?

• Work out what your variables are going to be.

• Which variables do you need to control?

• How you are going to display your results?

Write a report of your findings.

Figure 2.11 Which paper towel is the most absorbent?

ACTIVITY SHEETInvestigating temperatureSCI07SIAS07205


Understand

1 Consider the steps involved in the scientific method. Do you think this is a logical way to conduct scientific research? Explain your answer.

2 Explain what might happen if you left out one of the steps of the scientific method.

3 Would it matter if you changed the order of the steps of the scientific method? Explain any possible consequences.

4 What is a variable?


Apply

5 Consider an experiment to test whether the size of an ice block affects the time it takes to melt. For this experiment, what would be:a the hypothesisb the independent variablec the dependent variabled the controlled variables?

Reflect

6 Do you think some steps of the scientific method are more important than others? If so, which steps, and why?

Using online software, such as Gliffy or Draw Anywhere, create your own flowchart to show that you understand the steps of the scientific method. Upload your creation to the class wiki.

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glossary termsmeanaverage; the sum of all of the values divided by the number of values

raw dataall the data that is collected during an investigation

Data, and what to do with itSuppose that you have carried out an investigation and have collected your data. What will you do with the data? How will you analyse and present it so that other people will understand it?

Finding an averageFor some investigations, you will collect a large amount of quantitative data. It may not be appropriate to display all this raw data. In many cases, you will want to find an average value, or mean. To find the mean:• add all the data for one variable together to obtain a total• divide the total by the number of pieces of data.

For example, you may want to find out what is the average height of students in your class.

Figure 2.12 What is the average height of students in your class?

The data in Table 2.3 shows the heights of a group of students. Adding all the data gives:

163 1 158 1 172 1 180 1 163 1 150 1 168 1 175 1 155 5 1484

Dividing by the number of pieces of data gives:

Average height 5 total of heightsnumber of students

5 1484 9

5 165

The average height of the students is 165 cm.

Table 2.3 Height of students

Student Height (cm)

Alex 163

Brianna 158

Cam 172

Daniel 180

Dora 163

Ellie 150

Huang 168

John 175

Milly 155

Generating graphs Tables and graphs are often used to organise and present data. Graphs can provide a visual representation of the data that is more quickly understood than a large table. A graph often makes it easier to see patterns or trends in the data.

You can draw graphs by hand or on graph paper by using software such as Excel. Two of the most common types of graphs in science are the column graph (see Figure 2.13 on page 36) and line graph (Figures 2.14 and 2.15 on pages 36 and 37 respectively).

CONNECTION Maths: Choosing the right type of graphSCI07SICN07207

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Figure 2.14 A line graph is useful for measuring changes in a quantity over time.

Figure 2.13 A column graph is used for measurements that are not related to one another.

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Figure 2.15 Interpreting a curved line graph

Figure 2.16 Graphs of the same data using an unbroken scale (top) and a broken scale (bottom)

If you had to share one pearl of wisdom or one good idea about interpreting someone else’s graph, what would it be? Place your pearl of wisdom on the class wiki.

WEB 2.0 Sometimes an axis would be too long to fit on the page if it showed all possible values, starting at zero. Instead, a broken scale can be used. Look at the graphs in Figure 2.16; they show the same data but use different scales.

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Checking your data analysisYou can use the following checklist to help decide whether you have meaningful results that can be used to support or refute your hypothesis.

Is your data accurate?

Would repeating the investigation produce the same or similar results?

Is there enough data to support or refute your hypothesis?

Have you summarised your data with an average, if appropriate?

Have you checked that all your calculations are correct?

Have you used the most appropriate type of graph for your data?

Does your graph have a meaningful title?

Is the independent variable shown on the x-axis?

Is the dependent variable shown on the y-axis?

Are appropriate values and units of measurement marked along the axes?

Did you use an appropriate scale for each axis?

WEBLINKGraph analysis checklist

ACTIVITY SHEETGraphing checklistSCI07SHAS07220

Using a spreadsheet to create a graphActivity 2.8

WORKSPACEUsing a spreadsheet to create a graphSCI07SUWR07216

What to do

1 The following data shows the cooling of boiled water over 2 12 minutes. What type of graph would be appropriate for this data? Why?

2 Enter the data into an Excel spreadsheet.

3 Highlight the data and insert a chart. Select ‘Line’ and click on an option that shows the points, as well as the lines. Is this a suitable type of graph for this data? Explain.

4 Create a new graph using ‘X Y (Scatter)’. Is this a suitable type of graph for this data? Explain.

5 What have you discovered about using Excel to create a line graph?

Time (min) 0 0.5 1.0 1.5 2.0 2.5

Temperature (°C) 100 99 97 93 87 80


Understand

1 What are two different types of graphs? When are they used?

2 What does a broken scale on a graph indicate?

3 What variable is shown on the vertical axis of a graph? What is shown on the horizontal axis?

Apply

4 Look back at the data in Table 2.3 on page 35. Two other students were absent on the day the measurements were taken. Steven’s height is 167 cm and Anand’s height is 161 cm. Include this extra data and recalculate the average for the group.


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Writing a scientific report The report is a very important part of any scientific investigation. As well as describing your aim and presenting your findings and conclusions, your report must include a clear description of the steps you used. This allows other people to assess whether your method was a fair test and to check whether your investigation is repeatable. The scientific report has several important elements.

TitleThe title of your report needs to reflect what your investigation is about.

Aim The aim states the purpose of your investigation. It is expressed in general terms and often begins: ‘To investigate . . .’ or ‘To examine . . .’

Hypothesis The hypothesis is more specific than the aim. It is a statement that might or might not be true, often written in the form: ‘If . . . then . . .’ Your investigation will test the hypothesis by collecting data to support or refute it.

Materials This is a list of the equipment and materials you will need to carry out your investigation. It should include numbers and/or quantities. It is here that you discuss any safety risks and how you are going to manage them.

Method The method is a set of step-by-step instructions that show exactly what you will do to carry out your investigation. Remember that other people should be able to repeat your investigation using these instructions.

Results The results show what you have found in your investigation. If you have a lot of raw data, it can be shown in an appendix. (Raw data includes all your observations, both qualitative and quantitative.) The results section includes graphs that you have created from your data and any calculations you have made. This section is extremely important.

Discussion This is where your results are summarised, described and analysed. Any sources of possible mistakes or any problems encountered during the investigation are also discussed. However, the discussion relates only to the results that you obtained in the investigation. Do not discuss what should have happened or what you would have liked to happen.

Conclusion The conclusion is a clear statement of what your investigation found. Did your results support or refute your hypothesis? Remember that your results cannot prove your hypothesis – they can only support or refute it.

Appendix It you have a lot of raw data, you can present it in an appendix, usually in tables.

5 An activity in your science class required you to measure the temperature in your science classroom over a four-hour period. Your results are shown in the table on the right.a Show this data as a graph. b What was the lowest temperature during

the four-hour period?c What was the highest temperature during

the four-hour period?d From your graph, work out the

temperature of the room at 45 minutes.

Evaluate

6 Using your answer to Question 5, explain whether your choice of graph was the most suitable way to display the data.

Time (min) Temperature (°C)

0 14

30 16

60 19

90 21

120 21

180 23

240 17

ISBN 9780170214209

Nelson iScience 7

40

Example of a scientific report

Aim

To investigate the effect of fertiliser on the rate of growth of tomato plants.

Hypothesis

If a tomato plant has fertiliser added to the soil, then it will grow more quickly.

Materials• 6 tomato seedlings

• 6 small rectangular pots, each measuring 4 cm x 4 cm x 6 cm

• potting mix

• 100 mL measuring cylinder

• water

• fertiliser (Aquasol)

• electronic balance

• 30 cm ruler (showing millimetres)

Method

1 Fill each pot with the same type and amount of potting mix.

2 Plant one tomato seedling into each pot.

3 Measure and record the height of each seedling to the nearest centimetre. (These are the heights on day 0.)

4 Sprinkle 10 g of fertiliser onto the soil of three of the pots. Label these pots clearly.

5 Water each pot with 20 mL of water each day.

6 Measure the height of the seedlings (in centimetres) every second day.

7 Repeat step 6 for 2 weeks.

What are the risks in doing this activity? How can you manage these risks to stay safe?

Potting mix contains fungal spores that could be harmful to health.

Use potting mix in a well-ventilated area and wear gardening gloves.

Growing tomato plants with fertiliser

ISBN 9780170214209


41


Understand

1 Why is it important that scientific investigations are repeatable?

2 List the important elements of a scientific report.

Apply

3 In the tomato plant investigation above, what do we call the plants that did not

have fertiliser added to their soil? What is the purpose of these tomato plants?

4 Suppose that you used a different type of potting mix for each tomato plant. What effect might that have on your investigation?

5 What would have happened if one of the tomato plants had died during the investigation?

Reflect

6 Can you say conclusively that all tomato plants will grow more quickly if fertiliser is added? Explain your answer.


Results

The plants without fertiliser grew 34 2 19 5 15 cm.

The plants with fertiliser grew 38 2 19 5 19 cm (that is, 4 cm higher than the plants without fertiliser).

Discussion

Six tomato seedlings were grown under identical conditions, except that 10 g of Aquasol fertiliser was added to the soil of three plants. Results showed that the tomato plants that received the fertiliser grew 4 cm taller than the ones that did not. At weekends, neither plants received any water. As this affected all plants equally, the final results would not have been affected. Any future investigations of this type should include more plants under each condition. This would provide more data and also prevent problems arising if any of the plants died during the experiment.

Conclusion

Results from this experiment support the hypothesis that tomato plants with fertiliser added to their soil grow more quickly.

Table 2.4 Height of tomato plants

Day 0 2 4 6 8 10 12 14

Without fertiliser (cm) 19 20 23 26 28 29 31 34

With fertiliser (cm) 19 21 23 26 29 33 36 38

Appendix

42 ISBN 9780170214209

Understand

1 Explain the difference between qualitative and quantitative data.

2 Why is it important to gather data in a science investigation?

3 If you are designing an investigation, what factors must you consider to make it a fair test?

4 What is the purpose of Hazchem signs?

Apply

5 List three questions you would ask a research scientist about preparing for an investigation, recording data and reporting the results.

6 Write a hypothesis for each of the following questions.

a Why do my black clothes get hotter in summer than my white clothes?

b What would make my model car go faster?

c Will plants grow more if I give them more water?

Analyse

7 Olivia and Ethan decided to test whether red flowers lasted longer than white flowers. They put a red rose in a small cup of water on the bathroom shelf, and they put a white carnation in a large jar of water on the bench in the garden shed. After three days the white flower had died, but the red flower was still alive. They concluded that red flowers lasted longer than white flowers.

a Explain why this was not a fair test.

b Was Olivia and Ethan’s conclusion valid?

c Rewrite their method to make this a fair test.

Evaluate

8 In your opinion, what might happen if every scientist reported their scientific discoveries in a different way?

Reflect

9 Do you think it is important to write school science reports in a consistent way? Give reasons for your answer.

10 Should Hazchem signs be a global system, or just apply to a few countries? Explain your answer.

11 Finish this sentence using a science example: ‘I think it is important to know about . . . because . . .’

12 What are the implications for a scientist who claimed to have made an important discovery but did not follow the scientific method or write up a scientific report? Would that scientist’s findings be taken seriously?

Unit review

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