Skill Chapter 3 Scientific Method St. Stephen’s College F.3 Biology Mr. Tso

Skill Chapter 3Skill Chapter 3

Scientific MethodScientific Method

Skill Chapter 3Skill Chapter 3

Scientific MethodScientific Method

St. Stephen’s College F.3 Biology Mr. TsoSt. Stephen’s College F.3 Biology Mr. Tso

Scientific Method1. Introduction2. Asking questions3. Stating and testing hypotheses

A. What is hypothesis?B. How to test a hypothesis?

4. Designing and doing experimentA. What is an experiment?B. VariablesC. ControlsD. How to draw conclusion from experimental

results?E. Points to note in experimental design

IntroductionIntroductionIntroductionIntroductionThe knowledge of biology can be discovered by the ________ _______. The scientific method involves several major steps:

scientific method

Observation

Problem

Hypothesis

Prediction

Designing & performing experiment

Results

Conclusion

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Grasshoppers are commonly found in

grassland.

Grasshoppers are commonly found in

grassland.

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Why grasshoppers are normally found among

grass?

Why grasshoppers are normally found among

grass?

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Grasshoppers like to hide among green objects.

Grasshoppers like to hide among green objects.

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

If identical conditions are provided, grasshoppers will gather around green objects

most of the time.

If identical conditions are provided, grasshoppers will gather around green objects

most of the time.

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Variables:Variables:

Independent variableIndependent variable

Dependent variableDependent variable

colour of object colour of object

proportion of time a grasshopper stay on an object

proportion of time a grasshopper stay on an object

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Statement of the aim:Statement of the aim:

to determine the favoured colour for grasshoppers to stay on.

to determine the favoured colour for grasshoppers to stay on.

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Aspects to consider in designing procedure:Aspects to consider in designing procedure:

* position of objects * materials of the objects * smell of the objects * number of trials * others

* position of objects * materials of the objects * smell of the objects * number of trials * others

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

Dealing with Data:Dealing with Data:

* Table * Graph * Table * Graph

Observation

Problem

Hypothesis

Prediction


Results

Conclusion

The most favoured colour for grasshoppers to stay on is

green.

The most favoured colour for grasshoppers to stay on is

green.

IntroductionIntroductionIntroductionIntroductionObservation and Recording Data

Hypothesis

Design

Table

Graph

Conclusion

PredictionPerforming

Asking QuestionsAsking QuestionsAsking QuestionsAsking QuestionsScientific inquiry begins with the observation and recording of phenomena. The next stage in the process involves ______ _________ about these observations in order to explain the phenomena.

The questions posed define the ________ that the investigation takes.

asking questions

direction

Activity Time

Activity 1

Stating & Testing HypothesisStating & Testing Hypothesis(What is hypothesis?)(What is hypothesis?)

Stating & Testing HypothesisStating & Testing Hypothesis(What is hypothesis?)(What is hypothesis?)

This is a _________ (not a question) that attempts to provide _______ to the questions based on the observations.

statementanswers

Stating & Testing HypothesisStating & Testing Hypothesis(How to test a hypothesis?)(How to test a hypothesis?)

Stating & Testing HypothesisStating & Testing Hypothesis(How to test a hypothesis?)(How to test a hypothesis?)

The hypothesis should be testable by __________. A good hypothesis can be tested by experiment, the result of which support or contradict the accuracy of __________ based on the hypothesis.

experiment

predictions

Activity Time

Activity 2 & 3

Designing and Doing ExperimentDesigning and Doing Experiment(What is an experiment?)(What is an experiment?)

Designing and Doing ExperimentDesigning and Doing Experiment(What is an experiment?)(What is an experiment?)

It is an operation carried out under _________ conditions in order to discover an ________ effect.

controlledunknown

Designing and Doing ExperimentDesigning and Doing Experiment(Variables)(Variables)


Conditions which can change in an experiment are called ________. There are _____ different types of variables in an experiment:

variables three

(1) ___________ variableis the one which was deliberately changedIndependent

Dependent

Fixed

(2) _________ variableis the one which changed in response to the change of the independent variable.

(3) _____ variablesare all those conditions which do not change during the experiment.



It is vital that only ____ variable is manipulated each time. If more than one variable is manipulated, it is not possible to know which one is influencing the _________ variable.

one

dependent

Activity Time

Activity 4

Designing and Doing ExperimentDesigning and Doing Experiment(Controls)(Controls)


In order to draw valid conclusions from experimental results, the results of an experimental set-up have to be ________ with that of a ______ ______, which should be ________ to the experimental set-up in all respects except that the independent variables are not manipulated but kept ________.compared

control set-upidentical

constant

normal treatedA control may be defined as the set-up which is under _______ conditions. The ______ set-up is, therefore, the experimental set-up.

(3) It allows the ______ due to the fluctuations of environmental conditions to be corrected, as the fluctuations affect both the experimental set-up and the control set-up.

(2) It forms a basis on which the effect of the factor under testing can be _________ or _________.



The importance of the control:

(1) It confirms that a particular result is due to the _____ _____ ______ but not others.factor under testing

calculatedestimated

errors

Activity Time

Activity 6, 7 & 8

(2) If the value of factor X ________, the value of activity Y will also _______ / will ________.

OR

Designing and Doing ExperimentDesigning and Doing Experiment(How to draw conclusion from experimental results?)(How to draw conclusion from experimental results?)


A prediction is often written in one of the following two ways:

present

increasesincrease

decrease

occur(1) If factor X is _______, activity Y will _____.

The following ____ theoretical cases illustrate how _____ conclusion may be drawn from experimental results:

(Aim : to show that factor X is necessary for activity Y to be carried out.)



In reality, there should be _____ ____ one factor (X, A, B, C, D……. etc.) that could affect an activity (Y). That is to say factor X is only one of the many factors that could affect the activity Y.

more

fourvalid

than

Aim: to show that factor X is necessary for activity Y to be carried out.)



Case (1)Set-up (I) Set-up (II)

X, A, B, C A, B, C

was carried out

Factor X is necessary for activity Y to be carried out

was not carried out

Is there any difference in the initial conditions

between the two set-ups?Is there any difference in their results?





X, A, B, C A, B, C

was carried out

Factor X is not necessary for activity Y to be carried out

was carried out







X, A, B, C A, B, C

was not carried out

No conclusion can be drawn

was not carried out







X, A, B, C B, C

No conclusion can be drawn because the two set-ups differ in more than

one factor


between the two set-ups?

No matter what the result isNo matter what the result isNo matter what the result is




It can be seen that the ______ of case (4) is ____ because the experiment introduced _____ ____ one difference in the initial condition between set-ups.

design badmore than

It can also be seen that conclusion may be drawn only if results of two or more set-ups are compared.

Activity Time

Activity 5

(3) The potential problem due to _________ ________ is minimized by using a _____ sample size of organisms as far as possible.

(2) The set-up must be well designed so that it is ________.

Designing and Doing ExperimentDesigning and Doing Experiment(Points to note in experimental design)(Points to note in experimental design)Designing and Doing ExperimentDesigning and Doing Experiment(Points to note in experimental design)(Points to note in experimental design)

(1) The variables must be _________ so that the hypothesis can be tested.

controlled

workable

individualvariation large

Activity on Scientific Method

???? ??


Activity 1: Asking Question

(1) What was Fiona’s observation on the distribution of ants around different drops of sugary solution which she left on table carelessly?The number of ants gathered around different drops was different.

(2) What question was asked by Fiona?Why are there different numbers of ants around different drops?


Activity 2: Stating Hypothesis

What was Fiona’s hypothesis for her observation?Ants would choose sweet solutions.


Activity 3: Making Prediction

Base on Fiona’s hypothesis, what prediction can be made?If the concentration of sugary solution increases, the number of ants gather around will increase.

(Assumption: A more concentrated solutionis sweeter.)


Activity 4: Identifying the Variables

In Fiona’s experiment,

(1) What was the independent variable?It was the sweetness of sugary solution.

(2) What was the dependent variable?It was the number of ants gathered around each drop in one hour.

(3) What were the fixed variables?Size of each drop, type of the sugary solution, etc.


Activity 5: Drawing Conclusion

After the experiment, what conclusion could be drawn?Ants would choose sweeter solutions.

Activity on Scientific MethodActivity 6:The following set-ups are used in an experiment to show the uptake of oxygen by a respiring animal:

(1) The experimental set-up is tube ___.A(2) The control set-up is tube ___.B

1 0 m m 3 0

w ire g au ze

g rassh o p p er so d a lim e

m u slin b ag

cap illa ry tu b e o il d ro p

1 0 m m 3 0

A

B

Activity on Scientific MethodActivity 7:The following set-up is used in an experiment to study whether light is necessary for photosynthesis:

(1) The experimental set-up is region ___.A(2) The control set-up is region ___.B

S u n

reg io n B (g reen & ex p o sed )

reg io n A (g reen & co v e red )

Activity on Scientific MethodActivity 8:The following diagram refers to an experiment for studying the conditions for seed germination:

(1) The experimental set-up is beaker ___.B(2) The control set-up is beaker ___.A

S u n

m o i s tc o t t o n w o o ls e e d

A B

d r yc o t t o n w o o l



(I) (II)



(I) (II)

Case (1)

After one hour?



(I) (II)

Case (1) Can we draw a conclusion that grasshoppers like to stay on

green objects?



(I) (II)

Case (2)

After one hour?



(I) (II)


green objects?



(I) (II)

Case (3)

After one hour?



(I) (II)


green objects?



(I) (II)

Case (4)

After one hour?



(I) (II)


green objects?

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Skill Chapter 3 Scientific Method St. Stephen’s College F.3 Biology Mr. Tso