Developing a Scientific Plan(aka: The Scientific Method)
• Observe an unexplained phenomenon
• Form a Hypothesis
• Design Experiments
• Draw a Conclusion
• Report the Results
Observation• An Observation
is Gathered through your senses
• Something that you notice in the natural world
I see a red bird in my backyard.
Hypothesis• A testable explanation
of the observation
• A suggested solution to the problem
• Statement
• Sometimes it is an “If…then…”
If I see a red bird in my backyard, then it must be a cardinal.
Design an Experiment• A procedure to
test the hypothesis.
• Collect and record the Data
• Must be reproducible
• Watch the birds in my backyard everyday from 8am to 10 am
• Write down distinguishing characteristics of red birds
Draw a Conclusion• Compare actual
results to expected results
• Prior knowledge
• Reference Materials
• Everyday I saw a red bird with a crest and a black mask in the backyard
• I did not see any other red birds
• My observations matched the pictures of a cardinal in the field guide
• The red bird is a cardinal
Report the Results• Other
scientists can use the results
• Moves scientific discovery forward
• Results can be used to form a new observation and a new hypothesis
I will report my observations to the local ornithology club
How does salt and acid effect how fast an effervescent tablet will
dissolve?
Controlled Experiment
• Control group• Experimental
group or groups
• Plain Water
• Salt Water
• Cold Water
• Vinegar (Acid) Water
The Control Group
• The factor being tested is not applied to this group
• Serves as a standard
• Experimental group is compared to the control group
• Plain Water
Independent Variable• The one factor that will
change in an experiment
• The tested factor in an experiment
• Controlled and manipulated by experimenter
• Types of Water• Cold• Salt• Vinegar
Dependent Variable
• The factor measured in an experiment
• The value “depends” on the independent variable
• Observed or measured
•Time
Collect Data
• Use appropriate tools to collect the data needed to support the hypothesis
• Be as consistent as possible
• Be as complete as possible
Conclusion
• Use the data collected to support a concluding statement
• Ok if it does not turn out as expected
AccurateData gathered agrees with true
value.
Actual Number of Bluebirds in Field A
Observed Bluebirds in Field A on
June 14
Observed Bluebirds in Field A on
July 14
25 24 25
Worm Number Actual Length
cm
Measured Lengthcm
1 8.5 8.5
2 5.5 5.5
3 7.0 6.9
4 6.8 7.0
5 8.3 8.3
Accurate Measurement Example
Precise Repeated measurements show the same result.
Actual Number of Bluebirds in Field A
Observed Bluebirds in Field A on
June 14
Observed Bluebirds in Field A on
July 14
25 19 19
Worm Number Actual Length
cm
Measured Length
cm
1 8.5 7.5
2 5.5 4.5
3 7.0 6.0
4 6.8 5.8
5 8.3 7.3
Precise Measurement Example
Worm Number Actual Length
Measured Length
1 8.5 3.0
2 5.5 9.0
3 7.0 5.0
4 6.8 1.0
5 8.3 10.5
How about this data?
Worm Number Actual Length
cm
Student1
Student2
Student3
Student4
1 8.5 5.0 8.5 8.2 7.5
2 5.5 5.5 5.4 5.2 4.5
3 7.0 6.9 7.0 6.8 6.0
4 6.8 4.0 6.8 6.5 5.8
5 8.3 6.0 8.2 8.0 7.3
Which Student has the most precise data?
Which Student has the most accurate data?
What if I do not know what the actual value is?• Repeat the experiment several times
• Another experimenter repeats the experiment several times
• If the hypothesis is proven true time after time after time, then it becomes a THEORY
• If the theory is proven time after time after time after time, then the theory becomes a LAW