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BACKGROUND:

A hypothesis is a provisional or working explanation, assumed true only to guide experimentation or for the sake of argument. A theory is a well-established explanation

A law is just a description of a pattern in the data.

A theory is an explanation for the pattern.

The law shows what happens, without explanation. A theory explains how it happens, often by using an analogy or metaphor. So whether a hypothesis that becomes well established becomes a law or a theory depends on whether it tells you what happens, or it tells you how something happens.

A law (natural law) is a description of the data; it is not necessarily fact. If new data comes to light that violates the law, it must be amended or discarded. Because laws usually are based on a vast body of data, gathered over a long period of time and reviewed by many investigators, it's very rare for a law to be discarded. Apparent 'violations' of natural laws are easy to contrive if you ignore the restrictions on the data that the law is based on. When experimental fact is in conflict with a law, the law must be either corrected or discarded. This is a rare occurrence, because laws must summarize a large body of experimental data before they're elevated to law status. But it does happen.

The Scientific Method

A systematic procedure for solving problems and exploring natural phenomena

* Observations (data)

* Are the foundation of the scientific method

* Data can be qualitative or quantitative.

* Data is most useful when collected under controlled conditions

* Natural laws

* Compactly summarize patterns in a large amount of data

* Often apply only under special conditions

* Are descriptions of nature, not facts or explanations

* Hypotheses

* Tentative explanations designed to guide experimentation

* A useful hypothesis must be testable

* Must be rejected or corrected when they conflict with experiment

* Theories

• A well-tested explanation for experimental data based on a set of hypotheses.

• Must be discarded or refined when they can't explain new experimental results

• Scientific theories have three aspects: philosophical, mathematical, and empirical.

• Understand all three, or risk misusing the theory!

• A Good theory...

• Explains currently available data

• Is as simple as possible (but no simpler!)

• Accurately predicts results of future experiments

• Suggests new lines of work and new ways to think

• Clearly shows underlying connections

Scientific method Homework (Print and Complete)

1. A number of people become ill after eating dinner in a restaurant. Which of the following statements is a hypothesis?

a. Everyone who ate oysters got sick.

b. The cooks felt really bad about it.

c. Bacteria in the oysters may have caused the illness.

d. Symptoms include nausea and dizziness

e. People got sick whether the oysters were raw or cooked.

2. Which of the following statements is a law?

a. An egg cooked for 27 minutes in Baltimore was badly overcooked.

b. An egg takes less time to cook in Baltimore than in Denver.

c. Higher altitude means lower boiling points for water, all other things held equal.

d. An egg cooks in 17 minutes at sea level.

3. The statement, "Osmium has a density of 22.59 g/mL, which makes it the densest element known" is an example of:

a. A theory

b. An experimental observation

c. A hypothesis

d. A law

4. A natural law is

a. An explanation that has been proved

b. A description of a pattern or relationship in experimental data

c. A tentative explanation for a natural phenomenon

d. Obeyed under any and all circumstances.

On the other side of the page, select a personal experience that resulted in a meaningful decision. Discuss how you indirectly used the scientific method and possibly comment how you might have improved the outcome by following the method more rigorously.

(results will be confidential and only intended to help you see practicality of approach)

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