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