SNC 1D1 – The Nature of Science
The Scientific Method of Inquiry
What do scientists do?

Choose a question
to investigate
Research your
question
Invent a hypothesis
that will answer
your question
They ask questions about,
and make systematic
observations, of natural
phenomena.

They record observations
and conduct experiments
Design and
perform an
experiment that
will test your
hypothesis
Make observations
and collect data
where possible.
Analyze data

They use the data they
collect to develop models
that explain the
phenomena.
Does the data
support or refute
your hypothesis?

Form conclusions
Ask further
questions
They test their models
repeatedly, and discard,
refine, or confirm them.
The process of scientific inquiry begins with a GOOD QUESTION. What makes a good scientific question?
1.
2.
3.
4.
5.
6.
A good scientific question is on that can have an answer.
a. Why is there air?
b. What is the air made of?
A good scientific question can be tested by some observation or measurement that you can do.
a. Where did the universe come from?
b. How fast does a football move through the air when I throw it?
A good scientific question builds on what you already know.
a. What chemicals are needed to make radishes grow?
b. What is the source of mutations in Drosophila melanogaster?
A good scientific question can lead to other good questions.
a. What is the colour of the sky?
b. What events or conditions cause the sky to be blue (or orange)?
A good scientific question is specific and clearly worded.
a. Why do leaves turn brown?
b. Does the amount of water or sun a plant receives affect the colour of the leaf?
A good scientific question is linked to the topic that is being researched.
a.
b.
7. A good
a.
b.
8. A good
a.
b.
(If you wanted to learn about gravity, which would be a good question?)
What materials are best at keeping astronauts warm in space?
How do astronauts‟ bodies change when they are in a zero gravity environment?
scientific question could have many answers – it is not a simple “yes or no” answer.
Do plants grow in the dark?
What lighting conditions are best for plants to grow?
scientific question is one that you don‟t already know the answer to.
When is my birthday?
How is a planet‟s motion affected by the objects around it?
Which of the following are examples of GOOD QUESTIONS? Be prepared to explain your decision.
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Why do dogs bark?
How are students‟ grades affected by the amount of television watched?
What temperatures cause bacteria to grow the fastest?
What chemicals will prevent cut apples from turning brown?
Why are oceans salty?
Is the bounciness of a basketball related to the temperature of the ball?
Is protein synthesis affected when cells are placed in hypertonic solutions?
What types of materials best reduce friction on a skateboard wheel?
Is the rate of hair growth affected by the amount of protein someone eats?
Does baking soda and vinegar react?
How often does the sun rise?
Types of Scientific Inquiry
Controlled Experiment: when the purpose of an inquiry is to determine whether one variable causes an effect
on another variable. Example: How is the flow of electricity affected by the diameter of a wire?
Observational Study: when it is not possible to control variables in a study because it would be impossible, or
unethical. Example: How do volcanic eruptions affect respiratory (lung) health of a population?
Variable –
-
any factor that can affect the results of an experiment
a factor that can change or have a number of different values
Independent variable – one that is deliberately changed or selected by the investigator
Dependent variable – one that changes in response to the independent variable, but is not directly
controlled by the investigator
Controls – factors that are kept the same in a controlled experiment
Hypothesis
- A possible solution to a problem usually in the form of a prediction that can be tested.
- Sometimes written in the form of an “If …, then …” statement.
- Based on information collected about the problem (an educated guess).
- A null hypothesis (a hypothesis of „no difference‟) is often used
Experimental Design
- The hypothesis provides the framework for the design of the experiment
- It must be designed to provide a clear answer to the hypothesis, and involves the following steps:
o Identifying the dependent and independent variables
o Determining how the changes in the variables will be measured
o Specifying how to control the variables not being tested
o Selecting the appropriate technique, units and instruments to measure the variables
o Anticipating and addressing any safety concerns
o Deciding on a format for recording observations
Performing and Recording
- Procedures should be followed with care, but they may need to be modified if a problem arises
- Accurate observations at regular intervals should be made
- Observations can be made through the senses, or through some extension of the senses (such as with
a mechanical or digital sensor or instrument).
- quantitative observations – are based on measuring or counting – the right tool must be selected, but
it also must be used correctly to provide a precise and accurate measurement
- qualitative observations – are descriptions of qualities of objects or events, without the use of a
number or unit
Analyzing and Evaluating
- tables, lists and drawings of observations are not the final products for the data collected in an
investigation
- analyzing, or carefully studying the observations can provide more information than the raw data
itself
- plotting a graph of quantitative data is one of the methods used that will help to show a pattern or
trend in the data more clearly
- using mathematical analysis (statistics) is also used to look for trends in data
- analyzing also helps to identify any errors in measurement – sometimes a measurement might appear
very different from the others – if it is due to an error in measurement, it does not have to be
included in your analysis
- evaluating the evidence in an investigation helps to determine the quality of the investigation – this
depends on many factors such as the plan, the procedures, the equipment and materials, as well as the
skill of the investigator
Conclusions
- if the investigation has been designed properly, it will allow a researcher to determine if it supports
or refutes the hypothesis
- sometimes the conclusion must be that there is insufficient evidence to answer the question
- if the hypothesis is refuted does not mean that the investigation was a failure – it is just as valuable
- it is simply another step along the path of finding an answer to a problem
Communicating
- one of the important characteristics in scientific investigation is that scientists share their studies
with the rest of the scientific community – usually in the form of a report or a presentation
- before it can be published in a scientific journal, it must be examined by other scientists in a process
known as peer review.
- Clear and accurate communication is essential for sharing information – this allows other scientists to
repeat and verify the investigation – the more times a study is verified independently by others, the
closer it can come to becoming a theory
Theory
- a widely accepted explanation for a problem which continues to explain new observations when they
are tested – it explains “why”
Model
- a representation or description of a theory (helps to explain)
- a model may be mathematical (like an equation), it may be a diagram, or it may be a physical threedimensional model (like a solar system model).
Law
- a generalization of many observations
- the law does not explain anything, it only describes what happens
- For example, the Law of Gravity states that all objects attract one another (when you drop a pencil,
it falls toward the earth)
Understanding the Difference Between Observation and Inference
Observation
- A statement of fact that is made with the senses or through an extension of the senses
- Observations are objective – should not rely on past knowledge or influence from other ideas
Inference
- A statement using reason and knowledge to make sense of an observation.
- The more observations you have, the better an inference can be.
- For example: You look outside and observe that the street is wet. What are some possible
inferences?
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Cause and Effect
A lot of science deals with cause and effect variables. Here is an example:
An ice cream store sells more ice cream cones when the air temperature is higher. This is a cause – effect
relationship.
Cause variable:
Effect variable:
The cause variable is the independent variable in an experiment, and the effect variable is the dependent
variable.
Fill in the following to make more cause-effect relationships:
1. As the air gets more humid in the summer, people often
2. The more TV students watch in one day, the
3. The more candy children eat, the
4. It is difficult to walk on
Create two of your own:
5.
6.
because
because
because
because
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.
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SNC 1D1 – The Nature of Science
Analyzing Elements of the Scientific Method
Classify each of the following statements as a hypothesis, an observation or a theory.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Eating a lot of chocolate may cause pimples.
Humans and apes are descended from a common ancestor.
The interior of planet Neptune is made of green cheese.
If I hold a twenty dollar bill over a flame then it will burn.
Earth‟s average temperature is increasing due to greenhouse gases.
Steak is more expensive than hamburger.
Using as cell phone too much might cause brain cancer.
The planets Saturn and Uranus have several rings.
All matter is made of tiny particles.
If the colour of light is affects plant growth, then a plant under green light might grow differently
than a plant under red light.
Read each of the following statements and then answer the questions below.
1.
2.
3.
4.
5.
You and your friend are walking along a beach in Iqaluit on January 22, 2010, at 8:00am.
You notice on a thermometer on a nearby building that reads -2°C.
You also notice that there is snow on the roof of the building and icicles hanging from the roof.
You further notice a pool of sea water in the sand near the beach.
Your friend looks at the icicles and the pool and says “How come the water on the roof is frozen and
the sea water is not?”
6. You answer, “I think that the salt in the sea water keeps it from freezing when it is at -2°C.”
7. You go on to say, “And I think that under the same conditions, the same thing will happen tomorrow.”
8. Your friend asks, “How can you be sure?” You answer, “I‟m going to get some fresh water and some
salt water and expose them to a temperature of -2°C and see what happens.”
(a)
(b)
(c)
(d)
(e)
In which statement is a hypothesis made?
Which statement states a problem?
In which statement is an experiment described?
Which statements contain data?
Which statements describe observations?