The Scientific Method

The Scientific Method

Scientific Method

• Scientific method is a body of techniques for investigating events, acquiring new knowledge, or correcting and incorporating previous knowledge

• The scientific method is used to analyze events in an unbiased way.

Components of the Scientific Method

1. Question2. Hypothesis3. Experiment4. ConclusionScientific Method Monty Python.flv

1. Question

• The Question Refers to a specific observation– “Why is the sky blue”– In the movie, the question was “is she a witch?”

2. Hypothesis

• A hypothesis is an IF.. THEN.. statement.• A hypothesis is NOT an educated guess• In the movie the Hypothesis was “IFthe girl is

a witch THEN she will weigh the same as a duck.

3. Experiment

• A scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a known fact.

4. Conclusion

• If the experimental data validates the hypothesis consistently, then the hypothesis becomes a THEORY.

Scientific Law vs. Theory

What is a Theory?

What is a Law?

THEORIES NEVER BECOME LAWS!

Accuracy vs. Precision

• Q: Because the woman in the film weighed as much as a duck, does that make her a witch?

• NO, just because a hypothesis is true once does not make it accurate. A hypothesis must be tested over and over again and give precise results before it is accurate.

Accuracy vs. Precision

• Q: If we weighed the woman again on the same scales would we have the same the same result?

• Q: If we get the same results, isn’t the theory of the woman being a witch TRUE?

• NO, hypothesis must be tested in many different places with different reliable pieces of equipment.

Accuracy vs. Precision

• Accuracy and Precision.flv

Q1: If we weighed the woman again on the same scales would we have the same the same result? Is the test the villagers used accurate? Precise?

Q2: If we get the same results, isn’t the theory of the woman being a witch TRUE? Use your definitions of Accuracy and Precision to answer this question!

Accuracy vs. Precision

Accuracy vs. Precision

Variables (things that change)

Variables (things that change)

Variables (things that change)

Independent Variable (IV) vs. Dependent variables (DV)

• Independent Variable: Variable that is manipulated.– ALWAYS ON THE X AXIS (bottom axis)

• Dependent Variable: Variable that changes as a result of the independent variable.– The thing that’s measured – ALWAYS ON THE Y AXIS (side axis)

For example…

3M HCl with shell

2M HCl with shell

1M HCl with shell

Water with shell

Types of variables

• Independent variable (IV)– What we change on purpose (Eg. how acidic the water is)

• Dependent variable (DV) – What we measure as the result (Eg. How much shells have dissolved after 3 days)

• Controlled variables (constants) – What we keep the same to keep the experiment fair (Eg. The amount of acids and water; the type of shell; the temperature of the environment)

• In most experiments there is ONE independent variable, ONE dependent variable and many controlled variables

Remember…

• Cows Moo Softly– Change one thing- Independent– Measure one thing- Dependent– Keep everything else the same-

Constants

Controlled variables vs control

3M HCl with shell

2M HCl with shell

1M HCl with shell

Water with shell

• Independent variable - concentration of acid• Dependent variable – how much each shell dissolves• Controlled variables (constants) – time of experiment,

amount of acid and water, type of shell• Control – the water with shell, what we compare to