Observe and record
A
s scientists conduct their experiments, it is important always to keep records of
all measurements and observations made. Some observations are qualitative;
this means that they describe what is seen, such as ‘the gorilla protected itself in the
rain with a large leaf’. Quantitative observations are those where a measurement with
a specific value is made: for example, ‘the tranquillised gorilla weighed 162.5 kilograms’.
Inferring and predicting
Keeping a record
Scientists use observations to give
a logical explanation about what
happened and why it happened.
These inferences help them
predict what might happen in the
future. For example, inferences
may allow scientists to predict
when or where an earthquake may
occur. Predictions must be logical
and based on the quantitative and
qualitative observations made in
previous experiments.
Scientists studying the
endangered great white shark
combine qualitative observations
of sharks with quantitative
observations collected from tagging
and tracking sharks and studying
sharks caught in fishing nets. From
these observations, they infer why
sharks are found in certain areas,
what has attracted them and how
they will behave. The scientists then
predict where sharks might be
found in other regions and what
type of behaviour they might display.
When making observations, it is helpful to organise the data in a table.
Information presented in this way is often easier to read. Graphs can
then be constructed from the table to make it even easier to see patterns
and connections.
The heading for each column is a clear
label of what has been measured.
Distance (cm)
Time for ant to travel between markers (s)
0
0
2
3
4
7
6
8
8
12
Always
include
the units
used.
Use a ruler to
draw lines for
rows, columns
and borders.
Enter the data in
the body of the
table. Do not use
units in this part
of the table.
Graphing
Graphs are used to make data easier to interpret. The type of graph used
depends on the type of data to be displayed.
Other (10%)
Calcium (4%)
Oxygen (46%)
Iron (5%)
Aluminium (8%)
Pie charts are
useful for showing
the parts that make
up a whole. For
example, a pie
chart can be used
to show the
percentages of
different substances
in the Earth’s crust.
A great white shark is observed from the safety of
a cage on Dangerous Reef, South Australia.
Bar and column graphs
are used to display data that
is not continuous; one piece
of data does not relate
exactly to the next. For
example, a bar graph can be
used to show the number of
students in a class with a
particular hair colour.
Number of people
Silicon (27%)
10
8
6
4
2
0
Black
Brown Red
Colour of hair
Blond
14
Science Alive for VELS Level 5
Go to worksheet 1.3:
Animal features
Lines graphs have a horizontal
x-axis and a vertical y-axis. They
are often used to represent
continuous data. A line graph is
used to show how something
changes. For example, line
graphs could be used to show
how quickly a plant grows.
A line graph can be used to predict
what might happen in the future.
Height of plant (cm)
1.5
1.0
0.5
Are you a good
observer?
Michael Faraday (1791–1867) was a
scientist famous for discoveries in
chemistry and electricity. He made
53 observations of a burning candle
— how many can you make?
You will need:
matches
candle
Petri dish or jar lid
electronic scales or beam balance
beaker.
• Light a match and melt some
wax at the bottom of the
candle. Stick the candle to the
Petri dish.
• Cover the candle with an
upturned beaker.
2. Record more observations.
• Record the mass of the candle
and Petri dish again.
3. Was there a difference in the
mass of the candle and Petri
dish between your first and
second measurements? Explain
the result you achieved.
4. How many different
observations did you make?
5. Which of your observations
were quantitative?
6. As a class, construct a
table that lists the
observations of the
candle and the number
of people in the class
who recorded the
observation.
• Record the mass of the candle
and dish together.
• Light the candle.
20
30
Number of weeks
40
Line graphs are useful for working out
values between those that you actually
observed.
1. Write down as many
observations as you can. Use all
your senses except for taste. (No
chemicals should be tasted in a
science laboratory.)
THINK
4. Decide whether each of the following statements is
an observation, inference or prediction.
(a) A fire could be smothered using a blanket to
deprive the fire of oxygen.
(b) The candle goes out if I place a glass over it.
(c) Candles can’t burn without oxygen.
15
1. Science at work 1
7. Display the
completed table from
question 6 as a bar
graph.
5. Look carefully at the following photograph to
answer these questions.
(a) What do you think is the purpose of the
experiment?
(b) What qualitative and quantitative observations
might be made in this experiment?
(c) What special measuring equipment might be
used to help make quantitative observations of
the crash test?
REMEMBER
1. Are the following statements true or false? Correct
those you think are false.
(a) If we use a beam balance, we are making a
qualitative observation.
(b) A prediction is a logical guess about an event
that might happen in the future.
(c) By tracking sharks with an electronic tracer,
scientists can make quantitative observations.
(d) An inference is a logical explanation about what
occurred in an experiment.
2. Give an example of qualitative and quantitative
observations used by scientists studying sharks.
3. Which type of graph might be used to show a
prediction of how a trend may continue in the future?
✓ learning
10
I CAN:
understand what it means to infer and
predict
understand the difference between
quantitative and qualitative
organise data from observations into
tables and graphs.
Reporting
back
Temperature graphs
A graph is a useful way to present the results of an
experiment. A graph gives an overall picture of the
results. It can also be used to predict values that occur
between, or outside, those measured during an experiment.
The aim of this experiment is to show how the
temperature of water changes while it is heated over
a Bunsen burner.
cientists perform experiments to find
answers to their questions. When
their experiments are completed, they
write a report to tell others about their
work.
S
periment
Aim:
doing the ex
r
fo
on
s
a
A re
Materials:
t used
e equipmen
A list of th
ent
Method:
the experim
followed in
The steps
de
ements ma
Results:
s or measur
on
ti
va
er
s
The ob
:
Discussion
results
tion of the
na
a
pl
ex
An
:
gs
Conclusion
ts or findin
of the resul
An outline
You will need:
measuring cylinder
Retort stand
250 mL beaker
Bosshead
Bunsen
burner
heatproof
mat
matches
tripod
gauze mat
retort stand,
bosshead
and clamp
thermometer
clock
safety glasses.
The reports that
scientists write
include a lot of
information and
are often in the
format at left.
Clamp
Thermometer
Beaker
Gauze
mat
Tripod
Bunsen
burner
Box of
• Use a
matches
measuring
cylinder
to
measure
out
100 mL of water.
Heatproof
mat
• Pour the water into the beaker.
• Set up the equipment as shown in the diagram. Make
sure that the bulb of the thermometer is not on the
bottom of the beaker or out of the water.
• Wait for a minute to allow the thermometer to adjust to
the water temperature.
• Measure the temperature of the water. Record the
starting temperature in a table. The starting
temperature is recorded when time is 0 minutes.
Time (min)
Temp (°C)
Time (min)
0
6
1
7
2
8
3
9
4
10
Temp (°C)
5
16
Science Alive for VELS Level 5
Go to worksheet 1.4:
Practical report jigsaw
Hot and cold
• Put your safety glasses on.
• Light the Bunsen burner according to the rules
on page 8.
The highest air temperature ever measured
on Earth is 58°C. The measurement was taken in
1922 in Libya. The lowest temperature ever
measured was
in 1983 in
Antarctica.
That
temperature
was −86.6°C.
• Open the air hole and heat the beaker over a blue
flame.
• Measure and record the temperature of the water
every minute for 10 minutes.
• Turn off the Bunsen burner and allow the
equipment to cool.
• Plot a line graph of the data you have collected.
100
90
80
60
50
REMEMBER
1. Why do scientists write reports about the
40
30
experiments they conduct?
2. In which part of a laboratory report would a
20
graph of distance against time be drawn?
10
0
3. What is the difference between the results of an
1
2
3 4 5 6
Time (minutes)
7
8
9
experiment and the conclusions made?
10
THINK
4. Why would you not use a thermometer with a
• Join the data points with a smooth line.
scale from 0°C to 30°C for measuring the
temperature of your body?
1. Describe how the temperature of the water
changes over time.
INVESTIGATE
5. Does adding salt to water change the way the
2. How does your graph compare with the graphs of
other students?
temperature rises when the water is heated?
Design an experiment to test your answer. Pretend
that you are writing the start of a laboratory
report for this experiment. Write the aim, list of
materials and method in your workbook.
3. Use your graph to estimate the temperature of the
water four and a half minutes after heating started.
4. Predict the temperature that the water would have
reached 11 minutes after heating started.
• Write a report on this experiment. Ensure that you
include the aim, list of materials, method, results,
discussion and conclusion.
DESIGN
6. Scientists also use reports to explain experiments
conducted outside the laboratory. For example,
scientists working for car manufacturers write
reports on how cars crumple when they are
crashed against walls to test their strength.
Imagine that you were asked to present a
proposal for a test like this. Write an aim, list of
materials and method that you could include in
your proposal.
Extension
• Set up data-logging equipment with a temperature
probe. Your teacher will help you with this.
• As soon as the Bunsen burner is turned off, place
the temperature probe in the water.
• The data logger will record the temperature of the
water as it cools.
1. Describe the cooling graph.
2. List the advantages of using a data logger instead
of a thermometer to measure temperature.
17
1. Science at work 1
✓ learning
Temperature (°C)
70
I CAN:
write a laboratory report
measure temperature with a
thermometer
use tables and graphs
to record results.