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The Scientific Method and
Experimental Design
Unit 1 – LaboratoryMrs. Callender
Lesson Essential Question
How do I solve problems in chemistry?
Scientific Method
A logical approach to solving problems or
answering questions.
PARTS OF THE SCIENTIFIC METHOD
OBSERVATION/Research
HYPOTHESIS
EXPERIMENTTHEORY
LAW
Develop a Question.
ASK A QUESTION
Develop a question or problem that can be solved through experimentation.
BACK
Observations/Research
Make observations and research your topic of
interest.BACK
HYPOTHESIS
A proposed explanation of an observation.
An educated guess.
Must be testable.
Example of a Hypothesis….
Example: If soil temperatures rise, then
plant growth will increase.
???
BACK
EXPERIMENTDevelop and follow a procedure.
Include a detailed materials list.
The outcome must be measurable (quantifiable).
Modify the procedure if needed.
Confirm the results by retesting.
Include tables, graphs, and photographs.
BACK
Must include a Measurement.
23.5 cm
23.5 g
23.5 oC
1.0 g/mL
ObservationsQuantitative Qualitative
Descriptor.
Texture
Color
State of Matter
Smell
Sound etc.
Use Y
ou
r Sen
ses
Quiz YourselfOn a piece of paper write which of the following observations are qualitative or quantitative.
1. 50.0 cm 6. red car2. 100.0 oC 7. 1,000
Km3. Felt rough 8.
produced a gas4. 49 ants 9.
became solid5. Is a square 10.
0.58 g
Quiz YourselfOn a piece of paper write which of the following observations are qualitative or quantitative.
1. 50.0 cm Quant. 6. red car Qual.
2. 100.0 oC Quant 7. 1,000 Km Quant
3. Felt rough Qual. 8. produced a gas Qual.
4. 49 ants Quant 9. became solid Qual.
5. Is a square Qual. 10. 0.58 g Quant
BACK
The researcher is the observer, recording in a journal what he or she is seeing.
More Observations…Direct Indirect
The researcher must depend on the reported information from other researchers.
THEORY
A well tested explanation for a broad set of observations.
May use models.
May allow predictions.
Theories may change to explain new observations.
BACK
LAW
Presentation of results.
A statement that summarizes results of observations, but does not explain them.
Changes or is abandoned when contradicted by new experiments.
OV
ER
VIE
W
Lets Put it to the Test.
John watches his grandmother bake bread. He asks his grandmother what makes the bread rise.She explains that yeast releases a gas as it feeds on sugar.
Question...
John wonders if the amount of sugar used in the recipe will affect the size of the bread loaf?
Possible Question….
“How does sugar affect the rising of bread?”
Observation/Research
John researches the areas of baking and
fermentation and tries to come up
with a way to test his question.
He keeps all of his information on this topic in a
journal.
Develop a Hypothesis
Develop an Experiment, Theory and maybe a Law.
Everyday Example
Scientific Method Making Spaghetti Sauce
Observation Spaghetti sauce should be red.
Hypothesis (prediction)
Try a tomato sauce.
Test Heat pot of tomato sauce.
Observe result Taste the sauce - bland.
Revise hypothesis? Use tomato sauce and garlic!
New test? Add garlic, taste - not so bland.
Scientific Theory The Final Recipe.
Medical ExampleScientific Method
High Cholesterol
Observation Patient has high cholesterol
Hypothesis (prediction)
Certain chemicals may dissolve cholesterol deposits.
Test Give 100 patients these chemicals, give 100 patients placebo.
Observe result Same number lower their cholesterol as placebo patients.
Revise hypothesis?
Try different combo of chemicals.
New test? Re-run medical test. Observe results.
Scientific Theory
Lipitor reduces cholesterol.
Ex. Of Non Science Theory• Car won’t work? Aliens drained the
battery.• Spaghetti is bland? You were meant to
eat bland food.• Car won’t work? Gods must be angry.• Spaghetti is bland? At the instant of
tasting, tongue is transported to alternate dimension where all flavors are rendered nullified. Happens instantaneously.
No number of experiments can prove me right; a single experiment can prove me wrong.”
Albert Einstein
