Transcript Scientific Method

Scientific Method
S. Dickinson
Biology
2011-2012
In your notes, write about what you think of this
picture.
Think-pair-share
Get with a neighbor and share what you
wrote in your notes
Share with the class
What do you think the first
part of the Scientific
Method is?
What do you think the question was in this
experiment?
What will you use for comparison?
Scientific Method
Certain methods to obtain knowledge
 Ask questions… and then what?
 7 Steps
 Have you ever asked who, what, where,
when, how, or why? That’s the beginning.

What was the question?
Formulate a hypothesis. Write it in your notes.
What is changed on purpose?
Steps in the Scientific Method
1.
2.
3.
4.
5.
6.
7.
Use observations to identify a problem
Formulate a hypothesis
Construct a procedure (step by step directions)
Conduct your experiment
Collect and analyze data
Draw a conclusion
Repeat
Step 1: Use observations to identify a
problem
Observation
 Employs one or more of the 5 senses
 Direct or indirect

Can you use your senses directly to study electricity?
Step 2: Formulating a Hypothesis
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Testable statement
Evidence does or does not support the
statement
IF (put independent variable here), THEN (put
dependent variable here) statement
If the virus causes a deadly disease then introducing
that virus into healthy tissue will cause the tissue to
die.
 Rewrite your former hypothesis
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Not all hypotheses are in If, then format.
Independent vs. Dependent

Independent is manipulated
variable (what you change) ex. Light exposure, food, time,
depth, scent, etc.

Dependent is responding
variable (DATA) (what
happens due to the change) - ex.
Height, growth, amount of
oxygen produced, etc.
 REMEMBER:
D – dependent
R – responding
Y – axis
M – manipulated
I – independent
X – axis
Step 3: Procedure
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Step by step directions that are self explanatory
Number your steps
Be specific about equipment, amounts, units,
etc… but not wordy
Step 4: Experimenting
 Testing a hypothesis by gathering data
under controlled conditions
Controlled Experiment
 You change one factor or variable
and observe its effect on another while
keeping all other factors the same
or constant
Experimenting cont…
Constant: variables that stay the same through out
the experiment
ex. Same amount of water in all beakers, same sized
beakers, same plants…
Control: a sample that is treated like the other
experiment groups but the independent variable
isn’t applied (what normally takes place)
ex. You are testing a new drug. One group received
the drug; the other group was a placebo (sugar pill).
The group given the placebo is the control group.
Scenarios

As a group, analyze the scenarios to come up with:
 What
is the question being raised?
 Independent Variable?
 Dependent Variable?
 Control?
 Constant(s)?
 Write a hypothesis based on the scenario.
How do you collect data on this experiment?
Will it be the same for all experiments?
Step 5: Collecting and analyzing data
Forms of Data Collection:
1. Measuring

Quantitative data: data is measured in numbers
 Number of people in a group
 Measurements of a cube
 Duration of an event
2. Sampling

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Using a small part to represent an entire population
Must be large and random
Should include as many subjects as possible
Forms of Data Collection cont…
3. Organizing Data

Data is useless unless its organized
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Data table, graphs, chart, concept map
(appendix A)
Analyzing Data

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Process of determining whether data you collected
is reliable and if it supports your hypothesis or not
Data can be analyzed in several ways
Statistics to determine a relationship between the variables
 Compare the data with those obtained in other trials or
studies
 Determine sources of error

Analyzing Data cont.
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Data analysis shows general or specific trends or
patterns from a graph that you have created from
your data chart or table.
General Trend:
From 1955 to 1995, the total
amount of ozone
decreased from 325 d.u. to
169 d.u. in Antarctica.
Specific Trend:
From1964 to 1966, the total
amount of ozone
increased from 280 d.u. to
320 d.u. in Antarctica.
Step 6: Drawing Conclusions
1.
Create a Model
•
Constructing a representation of an object or process that
shows a relationship among the data
•
Visual, verbal or mathematical
Inferring
2.
Conclusion made on the basis of the facts or data
gathered during your experiment
Forming a Theory
•
May be formed after many related hypothesis have been
tested and supported by much experimental data
•
Broad and comprehensive statement that is thought to be
true
•
3.
Step 7: Repeat!
Make sure the data is accurate (you can
reproduce it)
Precision: how close you are to the
actual number
Do you think all steps are used all the
time and in the same order?
Think-pair-share
Ticket out the door – identify EXD
Ellen set up three identical ten-gallon aquariums. The
walls and tops were covered with black construction
paper to prevent light from entering. Ten feeder
guppies were added to each aquarium as test
subjects. A small corner of each aquarium was left
open, and a small reading light is placed over it. Each
day, the light is turned on over the aquarium, and
thirty seconds later, a small amount of food is added
to two of the aquariums. No food is added to the
third aquarium at this time. Every five days for twenty
days, the number of fish that come to the light before
the food is offered is recorded.