Transcript Investigative Process skills

Investigative
Process Skills
Evelyn Visagé
[email protected]
Copyright 2010
Investigative Process Skills
• Basic process skills Observation,
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measurement, using numbers, space/time
relationships, classifying, communicating,
recording/displaying data as well as inferring
(arriving at a conclusion) and predicting. This is
developed in Natural Science from primary
school.
Integrated skills such as identifying and
controlling variables, interpreting data,
operational definitions, application of theory,
forming hypotheses and experimenting are
normally only developed in your secondary
school years.
The Scientific Method
• Planning
• Obtaining evidence
• Analysis
• Evaluation
• Communicate findings
Aim
• We observe a Phenomenon (something in the
natural/material world), using our senses or
machines that are basically extensions of our senses.
or
• We have a Problem that we need to solve
Cake Recipe
• Ingredients
Cake flour
Eggs
Sugar
Milk
Salt
Cooking oil
Baking Powder
Vanilla
500 ml
4
375 ml
250 ml
2.5 ml
50 ml
15 ml
5 ml
METHOD
• Step 1: Heat the milk and cooking oil
• Step 2: Beat the eggs and gradually add
the sugar.
• Step 3: Sieve the flour and salt.
• Step 4: Add the flour, the milk and the
egg mixture.
• Step 5: Add the vanilla……
Ask questions
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Was the flour responsible for the height of the cake?
Was the milk responsible for the height of the cake?
Were the eggs responsible for the height of the cake?
Was the sugar responsible for the height of the cake?
Was the vanilla responsible for the height of the cake?
Was the baking powder responsible for the height of the
cake?
Was the oil responsible for the height of the cake?
Was the mixing responsible for the height of the cake?
Were the pans responsible for the height of the cake?
Was the oven responsible for the height of the cake?
Planning
Find the Variables
• Use the poster to “brainstorm”
• Identify the a) Independent variable
b) Dependent variable/s
c) Fixed/Control variables
Hypothesis
• Use the variables of the most promising question to
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formulate a hypothesis.
Hypothesis- General statement on what you expect to
find in the investigation.
Educated guess.
Answer to the question.
The hypothesis must be backed up Scientific evidence
The type of baking powder will change the
height of the cake.
Scientific Evidence
• Find out more about your intended
investigation. Preliminary
work/knowledge?
• Read books, magazines or ask
professionals who might know in order to
learn more about the area of study.
eg Baking powder/chemical reaction
• Keep track of where you get your
information from (for reference purposes).
Fixed/Control Variables
• Use all the considerations of variables ( in
the poster), to determine the most
important fixed variables.
• Eg
Oven
Mixing tool
Actual mixing
Person
Prediction
• Very specific – what you expect to happen
in this investigation
“A cake baked with Rosy’s Baking
Powder will be higher than one baked with
Mooring’s Baking Powder”
Method
• Discuss any preliminary work
• Write down your method – step by step
List of apparatus and
requisites
• List means like a “shopping list”
• Include the blanc table – set up for the
chosen independent and dependent
variables.
• Don’t forget a clip board!
Safety
• Take into account and discuss all safety
measures to be taken into account in the
investigation.
• Eg electricity and glass
Conducting
the
Investigation
Conducting the Investigation
• This means doing the actual experiment
• Record all numerical (measured) or
observed data – in the table
• Keep careful note of everything you do
and everything that happens.
• Write down all problems that you have
encountered.
• Write your data in the table.
Table
• Heading
A table to show the relationship
between the (dependent
variable)
and the (independent
variable)
• Column headings
Independent variable Left-hand side
Dependent variable/s Right-hand side
• SI units: / or ( )
• Arrange data of the independent variable
A table to show the relationship between the type
of baking powder and height of the cake.
Type of Baking Powder
Height of Cake (mm)
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Analysis
Analysis
• Look for a pattern (relationship) between
the variables/data in the table – ie
between the (dependent variable) and the
(independent variable).
• Decide on a suitable graph
• Draw/plot the graph
• Describe the pattern – between the
(dependent variable) and the (independent
variable)
The Graph
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Pie Chart
Line/curved graph
Scatter graph
Bar chart
Histogram
Column graph
Advanced levels of experimental science rely
heavily on graphical and mathematical analysis
of the data
Pie Chart
• Pie charts are drawn with the sectors
(slices of the pie) in rank order, largest
first, beginning at “noon” and proceeding
clockwise. Pie charts should preferably
contain no more than six sectors.
Bar chart
• Bar charts are drawn when the
independent variable does not have a
numerical value e.g. the number of
learners with blue, brown, hazel and black
eyes in a class.
• How to draw a bar chart:
• Bar charts are made up of data blocks or bars of equal width. These
bars do not touch each other. The spaces between the bars must
also be of equal width, although they are normally much narrower
than the bars. There is always a space between the first bar and the
y-axis.
• The independent variable is plotted on the x-axis and the dependent
variable on the y-axis.
• The axes should be fully labelled. Add appropriate units on the yaxis with brackets, a slash or solidus. There could be no units for
the x-axis as there are no numerical values.
• There must be a heading to explain what the bar chart shows. The
heading must contain both the dependent and independent
variables
Histogram
• When the independent variable is numerical and continuous from
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one extreme value to the other, you should draw a histogram. The
data is grouped into categories. Mass, length and shoe size of
learners in a class is a good example. In the case of mass, you
would start with the group of learners that have the smallest mass
and end with the group of learners that have the highest mass.
How to draw a histogram:
The categories or independent variable is plotted on the x-axis, as
bars.
The number of bars is determined by the number of categories into
which you group your data. Choosing the categories is very
important as your aim is to see a pattern. If there are too many
categories it might be difficult to see the pattern. A rule for
determining the number of categories is to take five times the log
of the total number of observations. Use your calculator to work
this out.
The bars of a histogram should be of equal width and touch each
other. The first bar should start against the y-axis.
• Choose an appropriate scale and mark out the x-axis, showing the
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edges of each data block. Label each bar with the appropriate range
of values.
Label the x-axis and add appropriate units with brackets, a slash or
solidus.
The dependent variable is plotted on the y-axis. In a histogram it
always represents the number or frequency.
Label the y-axis. Add appropriate units with brackets, a slash or
solidus.
There must be a heading to explain what the histogram shows. The
heading must contain both the dependent and independent
variables. A histogram to show the relationship between the
(dependent variable) and (independent variable).
The heading, axis’s, labels and units are written/drawn in black/blue
ink. The bars are drawn in pencil and then shaded or coloured
Column Graphs
• Column graphs are drawn when plotting
frequency graphs from discrete data, e.g.
frequency of occurrence of leaves with
different numbers of prickles or pods with
different numbers of seeds.
Line graph
• We often plot line graphs in Science! Both dependent and
independent variables have numerical values.
• How to draw a line graph:
• The independent variable will be plotted on the x-axis (horizontal)
and the dependent variable on the y-axis (vertical). Consider the
values and their position on the Cartesian plane. Draw them
in blue/black ink. Use as much of your graph paper/available space
as possible. Work out appropriate scales for each axis. Mark every
section with a small pencil line. We often change our scale while
deciding on the value of sections. If done by pencil one can easily
alter it. After you have finalised the scale, write the values at every
small pencil line with pencil. Remember – your scale must add/go
up in equal amounts, forming each section. It must accommodate
the lowest and highest value for each variable.
• Label each axis with the name of the physical quantity and the
appropriate SI unit e.g Time/s or Time (s).
• Points are plotted and clearly marked by crosses (x) or encircled
dots (o). Use the finest, sharpest, hardest pencil you can find (2H or
harder). Precision in this activity is of the utmost importance. Your
teacher/examiner checks these points when marking your graph.
Plot all the points first. You then have to carefully check and
consider what the graph will look like once the points are joined.
The graph is the whole diagrammatic presentation of your data. Do
you see any curves or do the plotted points lie in a straight line? If
there is a clear straight line (ie your values are directly
proportional), join the points with a ruler. If the points indicate a
curve, do not join them with a ruler. Join them by free hand. Use a
thin, sharp, hard pencil. No points must be plotted or joined with a
pen, fibre tip pen or colouring pencil.
• It may also well be that the plotted points lie in what
looks more or less (around) a straight line. This is a
special type of graph, commonly found in Physics. It is
called a scatter-graph. You draw a line that best fits all
the points with a ruler (if it looks like a straight line) and
a curve if all the the points together seems like they are
forming a curve.
• Label each axis with the name of the physical quantity and the
appropriate SI unit e.g Time/s or Time (s).
• Points are plotted and clearly marked by crosses (x) or encircled
dots (o). Use the finest, sharpest, hardest pencil you can find (2H or
harder). Precision in this activity is of the utmost importance. Your
teacher/examiner checks these points when marking your graph.
Plot all the points first. You then have to carefully check and
consider what the graph will look like once the points are joined.
The graph is the whole diagrammatic presentation of your data. Do
you see any curves or do the plotted points lie in a straight line? If
there is a clear straight line (ie your values are directly
proportional), join the points with a ruler. If the points indicate a
curve, do not join them with a ruler. Join them by free hand. Use a
thin, sharp, hard pencil. No points must be plotted or joined with a
pen, fibre tip pen or colouring pencil.
• It may also well be that the plotted points lie in what
looks more or less (around) a straight line. This is a
special type of graph, commonly found in Physics. It is
called a scatter-graph. You draw a line that best fits all
the points with a ruler (if it looks like a straight line) and
a curve if all the the points together seems like they are
forming a curve.
• Points are plotted and clearly marked by crosses (x) or
encircled dots (o). Use the finest, sharpest, hardest
pencil you can find (2H or harder). Precision in this
activity is of the utmost importance. Your
teacher/examiner checks these points when marking
your graph. Plot all the points first. You then have to
carefully check and consider what the graph will look like
once the points are joined. The graph is the whole
diagrammatic presentation of your data. Do you see any
curves or do the plotted points lie in a straight line? If
there is a clear straight line (ie your values are directly
proportional), join the points with a ruler. If the points
indicate a curve, do not join them with a ruler. Join them
by free hand. Use a thin, sharp, hard pencil. No points
must be plotted or joined with a pen, fibre tip pen or
colouring pencil.
Scatter-graph
• It may also well be that the plotted points lie in what
looks more or less (around) a straight line. This is a
special type of graph, commonly found in Physics. It is
called a scatter-graph. You draw a line that best fits all
the points with a ruler (if it looks like a straight line) and
a curve if all the the points together seems like they are
forming a curve.
Evaluation
Evaluation
• Carefully consider the results obtained in your
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investigation.
Do they support your Hypothesis?
Consider the equipment and methodology.
Summarise any difficulties or problems you had
doing the experiment
Were your readings/observations accurate
enough?
Were there any anomalous results? Discuss
• Do you need to change the procedure and
repeat the experiment?
• What would you do different next time?
• List other things you have learned.
Related questions
• You may be able to answer some of the
other questions
• Several new questions may have occurred
to you while doing the investigation.
• Questions lead to more questions which
lead to additional hypothesis that need to
be tested.
Accept/Reject Hypothesis
Make
recommendations for
further research
Evelyn Visagé
[email protected]
Communicate Findings
• Scientific Journals
• Popular magazines
• Newspapers
• Radio
• Television