Science is . . . like detective work

The important thing in science is not so much to obtain new
facts as to discover new ways of thinking about them.
Sir William Bragg (1862–1942)
CHAPTER
Science is . . . like
detective work
1
F
or detectives, science provides
a way of investigating. For
some people, science can be an
occupation; for others, science is
used to design, invent, build and
test things. But everyone uses
scientific knowledge or devices
made using scientific knowledge
every day. The word ‘science’
comes from the Latin word
scientia, meaning ‘knowledge’.
2
JAC A R A N DA S C I E N C E 1
Chapter focus
1. What does it mean to investigate scientifically? How is it like detective work?
2. How can we work effectively and safely in the science laboratory?
3. How can we be a detective to investigate and report on real-life questions?
4. What are the fields of science? How do they differ? What contributions to
the development of scientific ideas have been made by people from different
cultural and historical backgrounds?
?
What do we think and know already ?
Where’s the science?
Work in a small group for this activity. For each of the
photographs on this page, work together to write a
paragraph about how scientists might be involved in the
activity. Select a spokesperson to read the paragraph to
the class.
A scientist is . . .
If you were asked to draw a picture of a scientist, what would you
draw?
• Draw a picture of your ‘image’ of a scientist on A4 paper.
• Underneath the drawing, write a brief description of the scientist.
• Get together in a group and compare your drawings. Discuss the
drawings and decide what a single image of a scientist should look
like. As a group, either draw an image or write a description of a
scientist.
SCIENCE IS . . . LIKE DETECTIVE WORK
3
1.1
Detective skills
T
he way that a scientist approaches an investigation is very similar to the way detectives
investigate the scene of a crime. Scientists and
detectives both begin their investigations by first
asking questions about a topic.
A scientist may ask how longer life may be
obtained from a battery while a detective may ask
whether a crime has been committed. Many crimes
are solved and scientific breakthroughs are made
because someone has made careful observations.
Observations are pieces of information gathered by
the senses. A footprint, the smell of perfume, the
sound of a vehicle or a warm fireplace could all be
important observations in a criminal investigation.
On the basis of their observations, detectives and
scientists suggest possible explanations of their
observations, called inferences. For example, if
detectives recognised the smell of perfume at the
Who or what did it?
4
JAC A R A N DA S C I E N C E 1
scene of a crime, and they knew of someone who
had been previously convicted of burglary and who
wore that perfume, they might make the inference
that he or she might be the culprit.
Apply the first three steps of investigating scientifically to
the scene below.
1. Use the ‘5W’s and How’ strategy to generate as many
questions as you can about the scene.
2. Make observations (you will be able to use only your sense
of sight).
3. For each of your observations, make an inference about
how or why each one occurred.
>
MAK ING O B SE RV ATI ON S AND I NFER ENC ES
4. Quarter-fill a very small beaker with limewater. Gently blow
out through a drinking straw into the limewater.
When solving crimes, scientists often do tests on substances
in order to identify them. They make observations of the tests
and infer the substances’ likely identities.
AIMS
To make and record observations about changes that occur
when substances are mixed
To infer what is happening in each change
You will need:
test tubes
test-tube rack
50 mL beaker
spatula
eye-dropper
drinking straw
vinegar
sodium bicarbonate
sodium carbonate
copper sulfate
methylated spirits
limewater
starch suspension
iodine solution
safety glasses
5. Place a few drops of starch suspension in a clean test tube.
Add a drop of iodine solution.
• Draw up a table like the one below.
Activity
What we did
Observations
Inferences
CAUTION: Take care not to get iodine solution on your
skin or clothes.
1
• Perform each activity listed below and briefly record what
you did in the table. Use your senses of sight, hearing,
smell and touch during your observations and record them
in the table.
CAUTION: Safety glasses should be worn while
conducting these experiments.
1. Pour vinegar into a clean test tube to a depth of about 1 cm.
Add a spatula full of sodium bicarbonate.
Below is a list of inferences for each of the five activities.
Using your observations, determine which inference is the
best possible explanation for each activity and copy it into the
table.
A fine white solid formed in the solution.
The liquid evaporated and this caused cooling.
A blue solid formed.
A gas was formed and the white solid dissolved.
A dark blue–black solid was formed.
REMEMBER
2. Quarter-fill two clean test tubes with water. Add a dry
spatula full of sodium carbonate to one test tube. Shake
the tube until the sodium carbonate dissolves. Add a dry
spatula full of copper sulfate to the other test tube and
shake it until the crystals dissolve. Pour the contents of the
second test tube into the first.
1 How is a scientist like a detective?
2 What is the difference between an observation and
an inference?
3 Which of your five senses can be used to make
observations?
THINK
4 Read the following story and state whether each
3. Use an eye-dropper to place one
drop of methylated spirits onto
the back of your hand. Blow air
gently across the back of your
hand.
sentence is an observation or an inference.
(a) The dog in the house next door is barking.
(b) There are no lights on in the house.
(c) The owners must be asleep.
(d) There could be a prowler in the backyard.
(e) I heard the sound of breaking glass.
(f) The dog is still distressed.
(g) Someone is breaking into the house.
SCIENCE IS . . . LIKE DETECTIVE WORK
5
Identifying a person as a suspect is an example of a special type of
inference called a hypothesis. A hypothesis is a statement that can be
tested. When detectives name someone as a suspect, they are hypothesising that the suspect committed the crime. They will then test their
hypothesis by gathering further evidence and seeing if the evidence
supports their hypothesis. Scientists test their hypotheses by designing
and performing experiments (also called investigations) and gathering results. Look at the illustration on the right. When the owner
of the house came home, she found five CDs missing and her dog
barking and trying to jump up to the window. Formulate a hypothesis
about what happened.
If detectives gather more observations (such as a witness observing
the suspect running away from the house with stolen goods), they
would have more evidence to support their hypothesis and be able to
form a conclusion as to whether the suspect should be charged with
the crime. A conclusion is the final step of an investigation. Look at the
second illustration. The owner of the house has tested her hypothesis
by studying the garden beneath the window. She found footprints in
the garden bed and several crushed shrubs. Write your conclusion
about what you think happened.
Formulate a hypothesis about what happened.
Make a conclusion about what you think happened.
>
M A KING AND TESTIN G A H YPOTH E S IS
When people have a headache, they want relief as soon as possible. Can you help
them by coming up with a way to get their soluble aspirin to dissolve faster? Will
crushing a tablet affect the time it takes to dissolve? Why should it? Does the
amount of aspirin determine how long it will take to dissolve? To answer these
questions we will formulate a hypothesis and perform an experiment.
AIMS
To form and test a hypothesis about how crushing affects the time taken for an
aspirin to dissolve
To draw a conclusion from the experiment
You will need:
3 aspirins
mortar and pestle
3 beakers
timing device
Write down your hypothesis.
• Draw a table like the one on the right.
• Half-fill each beaker with cold water.
• Place a whole aspirin in one beaker, an aspirin split into three or four pieces into
Apply the next five steps of
investigating scientifically to the scene
above.
1. Select the inference you feel is most
likely and formulate a hypothesis.
2. Describe some of the data you would
gather and experiments you would do
to test this hypothesis.
3. Describe some possible results that
would not support your hypothesis.
4. State a conclusion for your
investigation given the results
described above.
5. Suggest an alternative hypothesis
that may be investigated further.
another beaker and a crushed aspirin into the third beaker.
• Record the time taken for each sample to completely dissolve and enter your
Time taken
to dissolve (seconds)
results in the table.
• Collect the results of two other groups and enter these into your table.
1. Summarise your results in a few sentences.
Aspirin
sample
2. Are your results consistent with those of the other two groups?
whole
3. Do the results support your hypothesis?
split into
3 or 4
4. Make a conclusion about the effect of crushing on the time taken for an aspirin to
dissolve.
6
JAC A R A N DA S C I E N C E 1
crushed
Group
1
Group
2
Group
3
Using hypotheses, experiments and conclusions can help you answer lots of questions.
The example below shows how Vanessa solved her problem scientifically.
Vanessa’s desk at home was in the sleep-out. She was often annoyed by the moths and flying ants that were attracted to
her white fluorescent desk lamp. When she was driving through town last night, she had noticed that there were no insects
flying around the yellow streetlights. She wondered if this observation provided a clue to overcoming her problem. She set
about working scientifically in the following way:
3TEP 3HE ASKED A QUESTION THAT
NEEDED AN ANSWER
(OW DO ) GET RID OF THE INSECTS
3TEP 3HE GATHERED RESULTS
!FTER TEN MINUTES THERE WERE LOTS AROUND MY LIGHT BUT FEW
AROUND MY BROTHER´S
3TEP 3HE MADE A CONCLUSION
-Y HYPOTHESIS ABOUT THE YELLOW LIGHT WAS SUPPORTED BY
THE RESULTS
3TEP 3TEP 3HE OBSERVED FEW
3HE FORMULATED A POSSIBLE
INSECTS AROUND YELLOW
ANSWER ° A HYPOTHESIS
STREETLIGHTS
9ELLOW LIGHT ATTRACTS FEWER INSECTS
3TEP 3HE DESIGNED AND PERFORMED AN EXPERIMENT
) WILL BORROW MY BROTHER´S LIGHT COVER IT WITH YELLOW CELLOPHANE AND
PUT IT ON THE OTHER SIDE OF MY DESK ) WILL COMPARE HOW MANY INSECTS
ARE ATTRACTED TO EACH LIGHT
REMEMBER
1 What is a hypothesis?
2 What has to be done before making a conclusion?
3 What is the difference between a hypothesis and a
conclusion?
(a) What question could he be trying to answer?
(b) Write a hypothesis for his experiment.
(c) Make up some results in a table that would not
support your hypothesis.
6 Josita had read that cut flowers last longer if the stems
are cut at an angle and some disinfectant is added to
the water. She designed an experiment and some of her
results are shown below.
THINK
4 Formulate hypotheses about the relationship between
the following pairs:
(a) doing gymnastics and a person’s flexibility
(b) the thickness of a candle and how quickly it is used
up when lit
(c) hair colour and how clever a person is.
5 Joseph is performing an experiment (see the illustration
below) for the benefit of his dogs. He takes the
temperature of two dog houses every 30 minutes.
aluminium foil
white sheet
Sample
Time before the flowers
began to wilt (hours)
flowers in tap-water
7.5
flowers with stems
cut at an angle in
tap-water
10.0
flowers in dilute
disinfectant
5.5
flowers with stems cut
at an angle in dilute
disinfectant
6.0
Make conclusions from her results.
thermometers
SCIENCE IS . . . LIKE DETECTIVE WORK
7
1.2
The science laboratory
S
cientific investigations sometimes occur in the science laboratory.
The science laboratory is similar to, but different from, most other
rooms and work spaces, in both its layout and its equipment.
Getting to know
the science lab
Laboratory
equipment
• Sit quietly for a minute or two
and look around the science
laboratory.
• List as many differences as
you can between the science
laboratory and other general
classrooms at your school.
• Draw a map of the science laboratory on a sheet of A4 paper,
labelling each of the following
items clearly.
Some of the equipment that you
are likely to use in the science
laboratory is illustrated on this
and the next page.
• Use the illustrations to find
each item of equipment in the
checklist on the next page. On
a copy of the checklist, place a
tick beside each item when you
have found it.
student tables and work benches
teacher’s desk or demonstration
bench
gas taps
power points
sinks
fume cupboard
eye wash
fire extinguishers
fire blanket
sand bucket
broken glass bin
rubbish bin
doors
A school science laboratory
8
JAC A R A N DA S C I E N C E 1
Some commonly used science equipment
Equipment checklist
Bunsen burner
heatproof mat
tripod
REMEMBER
1 What are the main differences between a science laboratory and a normal
classroom?
gauze mat
2 List the items of science equipment that are made of glass.
beaker
THINK
stirring rod
3 Which item of equipment would be used for each of the following
purposes?
evaporating dish
Item of
equipment
conical flask
Purpose
test tube
to heat substances
test-tube holder
to support beakers and similar containers of substances
while they are being heated
test-tube rack
spatula
retort stand
bosshead
clamp
filter funnel
tongs
safety glasses
measuring cylinder
to hold liquids that need to be swirled around or that have
been filtered
to hold small amounts of substances that need to be
heated or mixed
to hold a test tube while it is being heated
to move small amounts of solid substances from one
container to another
together with bossheads and clamps, to hold items of
equipment at a suitable height
to pour liquids from one container into another; can be
used with filter paper to separate some mixtures
to pick up and hold small, solid objects, often while they
are hot
4 What is the purpose of each of the following items of equipment?
Item of
equipment
Purpose
Item of
equipment
heatproof mat
test-tube rack
gauze mat
bosshead
beaker
clamp
stirring rod
safety glasses
evaporating
dish
measuring
cylinder
Purpose
INVESTIGATE
5 Find out what each of the following items is used for.
(a) Crucible
(b) Pipe-clay triangle
(c) Separating funnel
(d) Mortar and pestle
SCIENCE IS . . . LIKE DETECTIVE WORK
9
1.3
Playing it safe
T
he science laboratory can be a dangerous place if you are not
careful. There are certain rules that must be followed for your
own safety and for the safety of everyone else in the room.
DOs and DON’Ts
Do
Always follow your teacher’s instructions carefully.
Keep your workbooks and paper away from heating
equipment, glassware, chemicals and flames.
Tell your teacher immediately if you cut or burn yourself.
Tell your teacher immediately if you break any glassware
or spill chemicals. Spillages, even of water, need to be
cleaned up without delay.
Wait until hot equipment has had time to cool before
putting it away.
Leave all benches and tables clean and dry when you
have completed your experiments.
Wash your hands after you have handled any substance
in the laboratory.
Tie long hair back whenever you use a Bunsen burner.
Point test tubes away from your eyes and your fellow
students.
Wear safety glasses while mixing or heating
substances.
Don’t
Enter the laboratory without your teacher’s permission.
Run, push or behave roughly in the laboratory.
Eat or drink in the laboratory.
Smell or taste substances unless instructed to by your
teacher. When you do need to smell substances, fan
the odour to your nose with your hand.
Put paper, matches or other solid objects in the sink.
Pour substances down the sink. (Always follow your
teacher’s directions about the disposal of substances.)
Mix chemicals unless you have been instructed to by
your teacher.
Look directly into the top of a test tube, beaker or flask.
Enter a preparation room without your teacher’s
permission.
10
JAC A R A N DA S C I E N C E 1
REMEMBER
1 What should you do if you
cut or burn yourself in the
laboratory?
2 If you are asked to smell a
substance in a test tube, how
should you do it?
3 What item of safety equipment
should be worn while mixing or
heating substances?
THINK
4 Why is each of the following
laboratory rules necessary?
(a) Do not put paper, matches
or other solid objects in the
sink.
(b) Keep your workbooks and
paper away from heating
equipment, glassware,
chemicals and flames.
(c) Do not run, push or behave
roughly in the laboratory.
(d) Tie long hair back whenever
you use a Bunsen burner.
(e) Never smell or taste
substances unless
instructed to by your
teacher.
(f) Wear safety glasses
while mixing or heating
substances.
(g) Do not look directly into the
top of a test tube, beaker or
flask.
(h) Wash your hands after you
have handled any substance
in the laboratory.
(i) Do not mix chemicals unless
you have been instructed to
by your teacher.
5 Look carefully at the drawing on
the left and find all of the rules
that are being broken in the
science laboratory.
CREATE
6 Choose one of the laboratory
safety rules that you have
learned and draw a poster
that will illustrate the rule
clearly.
What’s wrong with this scene?
SCIENCE IS . . . LIKE DETECTIVE WORK
11
1.4
Which is the best?
U
sing the principles of scientific investigation can help
us make scientifically informed
decisions as consumers. When
investigating which is the most
effective dishwasher, sleeping bag,
thermos, detergent, shampoo etc.,
scientists seek to perform fair tests,
otherwise known as controlled
experiments.
The best burner?
The school science department
is looking to purchase a new set
of Bunsen burners. The most
important criterion is the ability
to heat liquids rapidly. There is
a choice of two brands, both of
which are on sale at the same
price. Can you help them to
investigate scientifically which is
the most effective?
>
BOUNC ING B A LLS
2. Make a list of all the variables that
AIM
To find which ball bounces the highest
You will need:
tennis ball
rubber ball (about the size of the tennis
ball)
cricket ball
baseball
any other ball that is about the same size
as a tennis ball
one-metre ruler
you can think of that need to be kept
constant (other than dropping height
and type of surface).
• Drop each ball from the same height
and measure how high each one
bounces. Now go ahead and answer
the question — scientifically!
3. Write a brief report about your
experiment. Ensure that you explain
your procedure in detail and include
a brief statement of the answer to the
question.
• The question you are trying to
answer is, ‘Which ball bounces the
highest?’ Prepare a table in which
to record your results.
1. Write down your hypothesis.
• Take care not to introduce
unwanted variables. Make sure
that the balls are dropped each
time. Don’t throw them down. Also,
think about which part of each ball
you will measure the height of the
bounce from.
Bouncing balls — which ball will bounce
the highest?
Ron and Stan designed and set up experiments to determine which burner is best.
Ron was in a rush and set up the experiment on the left. Stan had a plan and set up
the experiment on the right.
Ron’s Rush
A
Stan’s Plan
B
A
B
1. Whose experiment do you think would provide the most helpful results?
Which burner should the science
department buy?
12
JAC A R A N DA S C I E N C E 1
2. List the problems with Ron’s Rush and, for each, explain why it is a problem.
Factors that can affect the results of a scientific
test are called variables. The variable that is deliberately changed to answer the question is called the
manipulated variable. In the ‘Try this’ on page 12,
for example, the type of burner is the manipulated
variable. There are other variables that could affect
the rate at which the burner heats the water. Two of
these variables are the volume of water being heated
and the distance the burner is away from the water.
If these are not kept constant, any difference in the
rate at which each burner heats the water could be
due to these factors, rather than the type of burner.
So, for a question and hypothesis to be investigated
scientifically, all variables other than the manipulated
variable have to be kept constant. Variables that are
kept constant are called controlled variables. The
technique of investigating the effect of only one
variable at a time is called fair testing or controlling variables. An experiment that has all variables
controlled other than the one being investigated is
called a controlled experiment or fair test.
Some variables are difficult to keep constant.
When this occurs, the results of an experiment may
be unreliable.
Before investigating
which is the best
burner for ourselves,
we will need to know
more about them.
Some variables cannot be
kept constant. However, a
vacuum flask can help keep
the temperature of a drink
constant.
REMEMBER
THINK
1 What is a variable?
4 Amy and Nguyen are trying to find out whether
2 What is meant by the term controlling variables?
USING DATA
3 Simon and Jessie performed an experiment to find
out how effectively two plastic cups maintain the
temperature of near boiling water. Their measurements
are shown below.
stoneware or glass cups are better for keeping water
hot. The illustration below shows their experiment in
progress.
Amy and Nguyen’s
experiment in
progress
Comparing plastic cups
Time
(min)
Temperature (°C)
Simon’s cup
Temperature (°C)
Jessie’s cup
0
90
90
10
47
58
(a) List at least two weaknesses in their experiment
design.
20
29
39
(b) Make a list of all the variables that could affect the
results of Amy and Nguyen’s experiment.
30
22
31
40
20
26
(c) List any variables that Amy and Nguyen do not need
to control.
50
20
23
(a) Draw a graph to display the data in the table above.
(b) Which cup maintained the temperature of the water
more effectively?
(c) Estimate the temperature of the water in Simon’s
cup 15 minutes after timing commenced.
(d) Use your graph to estimate how long it would
have taken the water in Jessie’s cup to drop to a
temperature of 20 °C.
(d) Write a step-by-step outline of the procedure that
they could use to find out which cups keep water hot.
INVESTIGATE
5 How is the bounce height of a tennis ball affected:
(a) when it is damp
(b) when it is hot
(c) as it gets old and worn
(d) by different tennis court surfaces?
Design and perform an investigation to answer one or
more of these questions.
SCIENCE IS . . . LIKE DETECTIVE WORK
13
1.5
Hot stuff
W
hen you heat substances in the science laboratory, it is most
likely that you will use a Bunsen burner. A Bunsen burner
provides heat when a mixture of air and gas is lit.
barrel
Lighting a Bunsen burner
1. Place the burner on a heatproof mat.
2. Check that the rubber tubing is properly connected to the gas tap.
airhole
3. Ensure that the airhole is closed.
4. Light the match.
rubber tubing
5. Open the gas tap.
6. Hold the burning match just above the top of the barrel.
gas jet
gas
Introducing the Bunsen burner
You will need:
Bunsen burner, heatproof mat and matches
safety glasses
tongs
several pieces of porcelain (from a broken evaporating dish or crucible)
•
•
•
Examine a Bunsen burner and identify the parts labelled in the diagram above.
Draw your own labelled diagram of the Bunsen burner.
Put on your safety glasses and follow the steps in the ‘Lighting a Bunsen
burner’ box to light your burner.
1. What colour is the flame?
2. Does the flame make any noise?
•
Now turn the collar to open the airhole.
base
A Bunsen burner
The two f lames
The yellow flame of a Bunsen
burner is easily seen. So, when
the Bunsen burner is not being
used for heating, the yellow flame
should be used. The blue flame of
the Bunsen burner is much hotter
and cleaner but is more difficult
to see. The blue flame is used only
for heating.
3. What colour is the flame?
4. Does the flame make any noise?
5. Is the flame easier to see with the airhole open or closed?
•
Use tongs to hold a small piece of porcelain in the flame and record how long it
takes the porcelain to become red hot. Place the porcelain on the heatproof mat
to cool.
•
Repeat this procedure with several other pieces of porcelain in different parts of
the flame.
6. Which part of the flame appears to be the hottest?
•
Close the airhole and heat one of the cooled pieces of porcelain.
7. Does it become red hot?
8. Describe any change in the appearance of the porcelain.
14
JAC A R A N DA S C I E N C E 1
collar
The Bunsen burner has been
used in laboratories for about
150 years. It was invented by a
German chemist, Robert Bunsen
(1811–1899). The hottest part
of a Bunsen burner flame has
a temperature of about 1500 °C
— higher than the temperature
needed to melt gold! The inner
part of the blue flame contains
some unburnt gas and is much
cooler.
Using a
thermometer
Some hints for using thermometers
1. Make sure that you are using the right thermometer. For example, a
thermometer that reads only up to 50 °C will not be suitable for measuring
the temperature of boiling water (about 100 °C).
2. Ensure that the whole of the bulb of the thermometer is in the substance
that you are measuring the temperature of, and not resting on the bottom of
the container.
3. Wait until the column of liquid in the thermometer stops moving before you
read the scale. For example, a thermometer that has been in the air will take
a little while to reach the new temperature when placed in cold water.
4. When reading the thermometer, you should have your eyes level with the
top of the column of alcohol or mercury.
5. Record the temperature as soon as you have read it. Don’t wait.
6. Never stir with a thermometer.
A thermometer is used to
measure temperature in degrees
Celsius (°C). The thermometers
used in most school laboratories
contain alcohol with a red dye
added. Thermometers are easily
broken and need to be treated
with care. Do not put your thermometer down in a place where
it could roll off a table or bench.
If you are using a thermometer
containing mercury, a silver coloured liquid, extra care needs to
be taken. Mercury is a poisonous
substance.
CAUTION: If you break a
thermometer, report it to your
teacher immediately.
Estimating and measuring temperature
You will need:
school laboratory thermometer
250 mL beaker
paper towel
•
Estimate and then use the thermometer to measure the temperature of:
(a) air inside the school laboratory
(b) air outside the school laboratory
(c) refrigerated water in a small beaker
(d) cold tap-water in a small beaker
(e) warm tap-water in a small beaker
(f) under your armpit (take care, the thermometer is a delicate instrument).
CAUTION: Do not put the thermometer in your mouth!
•
Copy and complete the following table so that you can record your estimates
and measurements neatly.
Estimating and measuring temperature
Temperature (°C)
Substance or location
Estimate
Actual
air inside the school laboratory
air outside the school laboratory
refrigerated water in a small beaker
cold tap-water in a small beaker
warm tap-water in a small beaker
under my armpit
A school laboratory thermometer
SCIENCE IS . . . LIKE DETECTIVE WORK
15
W H ICH IS THE BE ST BURNER ?
>
List the variables that your group and your partner group will
need to control and decide how you will do this.
You will compare burners by testing which heats water in a
beaker the fastest. You will collaborate with another group
so that you can each test one burner and then share your
results. You will then take and record measurements of the
temperature of the liquid at one-minute intervals and draw a
graph to show how quickly the temperature changes.
AIMS
To form a hypothesis about which burner is likely to be most
effective
To design and perform a controlled experiment to test your
hypothesis
of the next page and put on your safety glasses.
• Use a 100 mL measuring cylinder to measure out 100 mL
of water and add it to the beaker without splashing. After
a minute or two, measure the temperature of the water
and record it in your table. This is the starting temperature
(time = 0 minutes).
1. Why don’t you measure the starting temperature as soon
as you have poured in the water?
• Light your Bunsen burner and adjust the collar to produce a
blue flame.
• Place it under the beaker and commence timing. You will
You will need:
Bunsen burner, heatproof mat and matches
250 mL beaker
retort stand, bosshead and clamp
safety glasses
tripod and gauze mat
100 mL measuring cylinder
school laboratory thermometer
need to quickly record the temperature every minute for ten
minutes.
• After ten minutes, turn off the gas to the Bunsen burner.
Wait a few minutes until your equipment has cooled before
putting it away.
The measurements you have made are called data (singular
= datum). It is often helpful to display your data on a graph.
Because the temperature of the water increased gradually, a
line graph is appropriate here.
Copy the following table and use it to record your
measurements.
• Copy the graph grid shown on the next page and carefully
plot your measurements on it. Plot each data point clearly,
and then join the points with a smooth curve.
Heating water in a beaker
Time
(minutes)
• Set your equipment up as shown in the diagram at the top
Temperature
(°C)
Time
(minutes)
0
6
1
7
2
8
3
9
4
10
Temperature
(°C)
2. Describe in words how the temperature increases.
3. Try to explain any unexpected results.
4. What would happen to the temperature of the water if you
heated it for another two minutes?
• If you have access to a computer and spreadsheet
software, you could enter your data into a spreadsheet and
print out a graph.
5. Share your results and graph with your partner group and
compare the rate with which temperature increases.
5
6. Make a conclusion about your hypothesis.
Reading the scale
A
B
C
50
D
F
E
50
G
H
I
25
25
24
40
24
40
80
30
50
40
40
30
30
24
23
30
23
23
70
22
70
22
The temperatures measured by thermometers A and B are 39°C and 23.6°C, respectively. What are the temperatures
measured by thermometers C to J?
16
50
80
24
23
J
JAC A R A N DA S C I E N C E 1
retort stand
bosshead
100
clamp
90
Temperature (oC)
80
thermometer
beaker
70
60
50
40
30
20
10
0
gauze
mat
1
2
3 4 5 6 7
Time (minutes)
8
9 10
Temperature of water heated in a beaker
tripod
Bunsen
burner
The ‘zero’ of the Celsius scale
is set at the freezing point of
water at sea level. The lower limit
of temperature is 273 °C. This
temperature is called ‘absolute
zero’.
box of
matches
heatproof
mat
The equipment needed for heating and measuring the temperature of a liquid in a
beaker
REMEMBER
1 Which flame of the Bunsen burner
2
3
4
5
should be used for heating?
List the six steps to be followed
when lighting a Bunsen burner.
Which is the hottest part of the
Bunsen burner flame?
Why is it safer to use the yellow
flame of the Bunsen burner while
the burner is not being used for
heating? Give two reasons.
There are two mistakes in the
following drawing. What are they?
There appears to be no upper limit
to temperature. The temperature
at the centre of the sun is about
15 000 000 °C. It is even hotter at
the centre of some stars that are
much larger than the sun.
6 What unit is used to measure
X reads from 34 °C to 42 °C.
temperature?
7 What are the temperatures
measured by the thermometers
shown below?
Y reads from 0 °C to 50 °C.
(a)
(b)
40
60
Z reads from 10 °C to 110 °C.
Which of the thermometers X, Y
and Z would be most suitable for
measuring the temperatures of
each of the following?
(a) Boiling water
(b) Sea water at the beach
30
20
(c) Your body
50
INVESTIGATE
10 What are the highest and lowest
THINK
8 Why should you light the match
before opening the gas tap when
lighting a Bunsen burner?
9 You have three different
thermometers X, Y and Z to choose
from. Each has a different scale.
air temperatures recorded by
weather observers? Where did they
occur?
11 Find out more about Robert
Bunsen. What were his
achievements other than the
invention of the Bunsen burner?
SCIENCE IS . . . LIKE DETECTIVE WORK
17
1.6
Reporting investigations
W
hen
scientists
conduct
investigations, they need to
write reports to tell other people
about their work. When you
conduct experiments, you need
to write reports that allow others
to understand what you did and
to read about what you found
out.
Your reports should include the
following sections.
Drawing science equipment
When reporting your experiments, a good, simple diagram can make it much
easier for the reader to understand what was done. There are some rules to
remember:
1. Diagrams in scientific reports should be drawn in pencil.
2. Straight lines should be drawn with a ruler.
3. Each item of equipment should be labelled.
The following diagram shows how some commonly used items of equipment
should be drawn.
Aim
A statement about why you did
the experiment.
Materials
A list of the equipment and
chemicals that were used.
Method
An account of what was done.
This will usually include a diagram showing how your equipment was set up. There should be
enough details included to allow
the reader to repeat your experiment.
tripod and
gauze mat
Bunsen burner and
heatproof mat
beaker
Results
A presentation of your data. This
might include a list of observations, or tables and graphs.
Discussion
An explanation of your results
and a description of any difficulties you had with the experiment.
This section might also include
suggestions for improvements to
the experiment.
Conclusion
A brief account of what you found
out and how your findings relate
to your aim. It is a good idea to
read your aim again before you
write your conclusion.
18
JAC A R A N DA S C I E N C E 1
conical
flask
test tube
retort stand,
bosshead and
clamp
filter funnel and
filter paper
Diagrams in scientific reports should be simple. In each case above, the apparatus is
shown on the left and the diagram of this apparatus on the right.
REMEMBER
1 Under which heading of your
report of an experiment should
the following information be
included?
(a) Suggestions for
improvements to your
experiment
(b) A reason for doing the
experiment
(c) Graphs and tables
(d) A description of what you
did
(e) A statement saying what
you found out by doing the
experiment
2 Draw a neat, labelled scientific
diagram of the following
equipment. Water in a conical
flask is being heated with a
Bunsen burner. The conical
flask is supported by a gauze
mat on a tripod. The Bunsen
burner is standing on a
heatproof mat.
THINK
3 Write a full scientific report on
the Which is the best burner?
investigation on page 16.
4 Draw a neat, labelled scientific
diagram of the two sets of
equipment that would be
needed to safely perform the
following activity.
Part 1:
Muddy salt water is being
poured from a beaker into
a filter funnel (with filter
paper). The filter funnel is
resting in the opening of a
conical flask.
Part 2:
The filtered salt water, now in
an evaporating dish, is being
heated by a Bunsen burner.
The evaporating dish is
supported by a gauze mat on
a tripod.
5 A hypothesis is often included
in a scientific report — usually
under the ‘aim’ heading,
immediately after the reason
for carrying out the experiment.
What is a hypothesis (see
pages 6–7)?
A good-quality report of an experiment
SCIENCE IS . . . LIKE DETECTIVE WORK
19
1.7
The f ields of science
B
ecause people work scientifically in so many diverse areas, science
is classified into smaller fields. The names of these fields describe
what is studied in each.
Science is . . .
biology
Science is . . .
physics
. . . the study of living things.
There are many branches of
biology. Zoology is concerned
with animals and botany with
plants. Entomology is the study
of insects while microbiology is
the study of living things that are
too small to see without
the help of a
microscope.
. . . the study of the behaviour of
natural and manufactured things
and reasons for their behaviour. Physics is concerned with
movement and different forms
of energy such as light, heat,
electricity and nuclear energy.
Branches of physics include
acoustics, the study of sound,
and biomechanics, the study of
the forces involved in human and
other animal movement.
Science is . . .
chemistry
Science is . . .
geology
. . . the study of the Earth and
how it changes. A geologist might,
for example, be concerned with
how mountains are formed or
with using rocks to trace the
Earth’s history. Vulcanology, the
study of volcanoes, seismology,
the study of earthquakes, and
palaeontology, the study of fossils, are some of the branches of
geology.
Science is . . .
astronomy
. . . the study of the stars, the sun,
the planets, their moons and other
heavenly bodies such as comets
and asteroids.
. . . the study of substances, what
they are made of, how they
are formed, how they change
and what happens when they
are combined. Branches of
chemistry include radiochemistry, the study of
radioactive
substances,
and pharmacology, the
study of the effect of
drugs on living things.
An astronomer at a control desk of
CSIRO’s Australia Telescope Compact
Array. Computers are used to control the
movement of the telescope as it follows
its target. © CSIRO
Science is . . .
ecology
Physics can be used to explain the movement
of a windsurfer.
20
JAC A R A N DA S C I E N C E 1
. . . the study of the way that living
things interact with one another
and with the world around them.
The people of science
Some scientists work in more than one area at a time. For example, a
biochemist works in biology and chemistry, studying the substances in
living things. A biophysicist might study the small electrical signals that
travel from your ear to your brain, which enable you to hear. Scientists
work in a variety of situations — indoors or outdoors, in laboratories,
in factories, on ships, in planes, underwater or even in outer space.
Science is . . . everywhere!
Scientific knowledge is all around you. Whenever you turn on a light,
eat food, watch television or flush the toilet you are using the products
of scientific knowledge.
Nurses, police, dietitians, teachers, doctors, vets, mechanics, gardeners, stage designers and artists use scientific knowledge. In fact
you could easily add to this list yourself. For example, engineers use
scientific knowledge to design bridges, computers, factories, artificial
limbs, sewerage systems and buildings.
Science and
technology
Since prehistoric times, people
have been making scientific discoveries that have improved the
quality of life. The use of scientific
ideas to make devices that make
life easier is called technology.
The invention of the wheel is a
good example of early technology.
The scientific idea behind the
wheel is that objects roll over
surfaces more easily than they
slide across them. The interaction
of science and technology has
been the driving force behind our
modern technological world.
You use scientific
knowledge every day.
Not all scientists were high
achievers at school. Some very
famous scientists were average
or below average school students.
Albert Einstein is probably the
most famous example. He did not
talk until he was three years old.
He left school at the age of 15 and
went back later. He passed his
university exams by studying the
notes of his classmates.
THINK
2 What would each of the following types of scientist be
1 Use a table like the one below to write down how people
in each of the following occupations might use science
in their daily work.
nurse
chef
journalist
mechanic
vet
farmer
gardener
architect
police officer
nurse
chef
journalist
3 List five devices that you have used today that would not
have been invented without scientific knowledge.
IMAGINE
4 Imagine that you are given the chance to interview
Science is everywhere
Occupation
mainly concerned with?
(a) Biochemist
(b) Geophysicist
(c) Marine ecologist
How science is used
any scientist from the past or present. Who would you
choose? Give reasons for your choice and prepare a list
of questions that you would ask.
INVESTIGATE
5 What do the initials CSIRO stand for? What does this
organisation do?
6 Find out what you need to study at school and
afterwards to become a scientist or engineer.
SCIENCE IS . . . LIKE DETECTIVE WORK
21
1.8
Greats from the past
W
ho is the greatest scientist of all time? Is it Curie, Einstein,
Newton or Pasteur? Or is it one of the people who saved
millions of lives by discovering X-rays, penicillin or vaccination?
The slow starter
Albert Einstein (1879–1955) is
most well-known for his theory
of relativity (there are actually
two theories of relativity) and the
equation E = mc 2, which describes
the relationship between mass
and energy.
Albert Einstein was certainly a
slow starter. Although he was fascinated by mathematics, Einstein
performed badly at school and
left at the age of 15. He returned
later and trained as a teacher in
Switzerland. Einstein often failed
to attend lectures and passed
university exams by studying the
notes of his classmates.
Einstein’s first job was as a
junior clerk in a patent office. His
work was not demanding and he
spent a lot of time doing ‘thought
experiments’.
At the age of 26, Einstein began
to publish his ideas. These ideas
altered our view of the nature of
Einstein’s first wife, Mileva, was a
mathematician. He discussed many of
his new ideas with her.
22
JAC A R A N DA S C I E N C E 1
Did that apple
really fall on his
head?
the universe by changing existing
Sir Isaac Newton (1642–1727) is
laws and discovering new ones.
Einstein explained the photo- probably most well-known for his
electric effect, in which light laws of gravitation, which explain
energy is transformed into elec- the motion of the planets around
trical energy, and was awarded the the sun. According to some
Nobel Prize in Physics in 1921 for historians, his ideas about gravity
arose after an apple fell on his
this explanation.
Einstein’s theories of relativity head. We’ll probably never know
were so different from earlier if this is true.
Isaac Newton was sent to
theories about the universe
Cambridge
University at the age
that they were not believed or
understood by most scientists. of 18. When the university closed
His theory of special relativity down in 1665 as a result of the
explains the behaviour of objects Great Plague, young Isaac went
that travel at speeds close to the home for two years. There he
speed of light. His theory of gen- developed his laws of gravitation
eral relativity explains the effect of and his three laws of motion.
gravity on light, and predicts that During his life, he also made
time ‘slows down’ in the presence discoveries about the behaviour
of large gravitational forces. These of light and invented a whole new
theories provide useful clues branch of mathematics, called
about the development and future calculus. Much of the scientific
knowledge that has been acquired
of the universe.
Einstein’s theories suggested since the seventeenth century is
that mass could be converted built upon Newton’s discoveries
into energy. This idea led to during that amazing two-year
the development of the atomic period.
bomb and nuclear power.
Einstein, who was
Jewish, fled Germany
in 1933 to live and
work in the United
States. Einstein
was an active
opponent of nuclear
weapons, and was
involved in the
peace movement
long before atomic
bombs destroyed
Hiroshima and
Nagasaki at the
Did that apple really fall on his head?
end of World War II.
A family affair
Marie Curie (1867–1934) became the first scientist to win two Nobel
Prizes when she was awarded the Nobel Prize in Chemistry in 1911
for her discovery of two new elements, polonium and radium. Radium
was used in the treatment of cancer until cheaper and safer radioactive
materials were developed. Marie Curie’s first Nobel Prize, for the study
of radioactivity, was shared with her husband, Pierre, and fellow
scientist Antoine-Henri Becquerel in 1903.
As a child, Marie Sklodowska (her birth name) wanted to study
science. However, girls were forbidden to attend university in her
native country of Poland. She worked as a private tutor for three years
so that she could earn enough money to study at the University of
Paris. It was there that she met her future
husband, Pierre. They were very poor and
spent most of their money on laboratory equipment, leaving them with very
little money for food. In fact, they often
couldn’t afford to eat. After Pierre was
knocked down and killed by a speeding
wagon, Marie continued her research
in radioactivity, pioneering the development of radioactive materials for use in
medicine and industry. She became the
first female teacher at the University of
Paris and worked hard to raise money for
scientific research.
Marie Curie in her laboratory
The germ of an idea
Louis Pasteur (1822–1895) proved that infectious diseases were caused
by microbes. His ideas became known as ‘germ theory’. He also developed several vaccines that made people immune to diseases such as
rabies and smallpox. In doing this, he has been responsible for saving
the lives of millions of people and countless animals.
Pasteur began his scientific career in physics and chemistry, but
became interested in microbes when he was using light to investigate
the differences between chemicals in living and non-living things.
Pasteur’s next challenge was to rescue the French wine industry.
Wine (and beer) became sour very quickly and this was beginning
to have an impact on the French
economy, which relied heavily on
the export of wine. Pasteur showed
that the souring was caused by acids
produced by the action of bacteria
in the wine. Pasteur invented a
process that rapidly heated some
of the ingredients of the wine. The
rapid heating killed most of the
offending microbes without altering
the flavour of the wine. The process,
known as pasteurisation, was later
Pasteur removed the body fluids of
rabbits infected with rabies and made
adapted to slow down the souring of
a vaccine for the disease from their
milk.
dried-out bodies.
THINK
1 Quickly make a list of your
‘Top 3’ scientists of all time. For
each one, answer the following
questions.
(a) What impact does their
work have on your life?
(b) Did they just happen to be
in the ‘right place at the
right time’?
(c) Did they work under adverse
conditions?
(d) Did their work save lives?
(e) Did their work have any
destructive influence?
(f) What other special qualities
make them great?
2 Is it fair to select the single
greatest scientist of all time?
Explain your answer.
3 Louis Pasteur conducted many
of his experiments on animals.
Many of them would now be
considered cruel. However, the
experiments saved many human
lives.
(a) Present the arguments
for and against the use of
animals in such experiments.
(b) In your opinion, were
the animal experiments
justified? Write a brief
statement supporting your
opinion.
IMAGINE
4 Imagine that you are one of
the three scientists that you
have chosen as the greatest
scientists of all time. Write a
short speech (3–5 minutes)
about your life and work, and
deliver it to your class. Illustrate
your speech with models,
diagrams or photographs.
INVESTIGATE
5 Write a biography similar to the
four presented on these pages
about one of the following
scientists:
Michael Faraday (1791–1867)
Charles Darwin (1809–1882)
Lise Meitner (1878–1968)
Barbara McClintock (1902–1992)
Peter Doherty (1940– )
Stephen Hawking (1942– )
SCIENCE IS . . . LIKE DETECTIVE WORK
23
Looking back
What I know about science
1. Take some time to think about all you have
learned while working through chapter 1 by
completing the following two tasks.
(i) Fill in a table like the one below in your
workbook. You might find it useful to
reflect on the ‘Chapter focus’ questions at
the start of the chapter on page 2.
Main ideas
Facts I have learned
JAC A R A N DA S C I E N C E 1
90
18
80
17
70
16
Skills I have learned
(ii) Make a list of skills that you think you
need to practise more. Then make sure
you take the time to improve in the areas
you listed.
2. Kimberley and Glenn were walking past
their neighbour’s house when they noticed
that a front window was broken. Glenn told
Kimberley that somebody had probably
thrown a ball through the window. They
had a closer look and noticed clothes
scattered all over the floor and drawers
open. Kimberley noticed some blood on the
broken glass. She told Glenn that the house
had been burgled. Glenn agreed and they
called the police.
(a) List the observations that were made.
(b) Who suggested a hypothesis?
(c) What was the hypothesis and why was it
suggested?
(d) What conclusion was reached by Kimberley
and Glenn?
24
(e) Suggest a different conclusion based on the
observations that were made.
3. Huang and Tina conducted an experiment
to find out if radish plants grow better in
the shade. They placed three plants under a
veranda at the back of the house and another
three in a sunny place in the front yard. All
plants were planted in the same soil. Huang
and Tina watered each of the plants equally
each day.
(a) Did they conduct a fair test?
(b) How could Huang and Tina improve the
design of their experiment? List as many
improvements as possible.
4. What is the temperature measured by each of
the two thermometers shown below?
5. What does each of the following scientists
study?
(a) Chemist
(b) Biologist
(c) Seismologist
(d) Biochemist
(e) Entomologist
(f) Botanist
(g) Zoologist
(h) Vulcanologist
(i) Physicist
(j) Astronomer
6. Which of the scientists listed in question 5
could be correctly described as geologists?
7. Name each of the items of equipment below.
(a)
(b)
(c)
(c)
9. Create an affinity diagram like the one below
to sort the equipment listed on page 9 into
groups. Each item should be listed in only one
group. If an item has more than one purpose,
list it in the group corresponding to its most
important purpose.
(d)
(e)
(f)
(g)
8. The affinity diagram below organises some of
the ideas used by scientists into four groups.
Each category name is a single word and
represents an important part of scientific
investigations. However, the category names
have been jumbled up. What are the correct
categories for groups A, B, C and D?
10. Create an affinity diagram that shows what
different types of scientists study. Choose four
of the following types of scientists to use as a
category heading: biologist, physicist, geologist,
astronomer, chemist, ecologist.
11. The steps used
LIGHTING A BUNSEN BURNER
to light a Bunsen
burner can be
Place the Bunsen burner
displayed as a
on a heatproof mat.
flowchart, as shown
on the right. Use the
information in the
Check that the rubber
tubing is connected
flowchart to create a
properly to the gas tap.
storyboard with six
scenes to show how
a Bunsen burner
Ensure that the airhole is
is lit correctly and
closed.
safely.
12. Create a storyboard
that tells the story
Light the match.
of the main events
in the life of one
of these famous
Open the gas tap.
scientists.
(a) Albert Einstein
(b) Sir Isaac Newton
Hold the burning match
(c) Marie Curie
just above the top of the
(d) Louis Pasteur
barrel.
SCIENCE IS . . . LIKE DETECTIVE WORK
25